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class="vector-toc-list"> </ul> </li> <li id="toc-Cleavage" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Cleavage"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Cleavage</span> </div> </a> <ul id="toc-Cleavage-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Blastulation" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Blastulation"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.3</span> <span>Blastulation</span> </div> </a> <ul id="toc-Blastulation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Gastrulation" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Gastrulation"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.4</span> <span>Gastrulation</span> </div> </a> <ul id="toc-Gastrulation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Organogenesis" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Organogenesis"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.5</span> <span>Organogenesis</span> </div> </a> <ul id="toc-Organogenesis-sublist" class="vector-toc-list"> <li id="toc-Neurulation" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Neurulation"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.5.1</span> <span>Neurulation</span> </div> </a> <ul id="toc-Neurulation-sublist" class="vector-toc-list"> <li id="toc-Primary_Neurulation" class="vector-toc-list-item vector-toc-level-4"> <a class="vector-toc-link" href="#Primary_Neurulation"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.5.1.1</span> <span>Primary Neurulation</span> </div> </a> <ul id="toc-Primary_Neurulation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Secondary_Neurulation" class="vector-toc-list-item vector-toc-level-4"> <a class="vector-toc-link" href="#Secondary_Neurulation"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.5.1.2</span> <span>Secondary Neurulation</span> </div> </a> <ul id="toc-Secondary_Neurulation-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> </ul> </li> <li id="toc-Larval_and_juvenile_phases" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Larval_and_juvenile_phases"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.6</span> <span>Larval and juvenile phases</span> </div> </a> <ul id="toc-Larval_and_juvenile_phases-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Metamorphosis" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Metamorphosis"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.7</span> <span>Metamorphosis</span> </div> </a> <ul id="toc-Metamorphosis-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Adulthood" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Adulthood"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.8</span> <span>Adulthood</span> </div> </a> <ul id="toc-Adulthood-sublist" class="vector-toc-list"> <li id="toc-Senescence" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Senescence"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.8.1</span> <span>Senescence</span> </div> </a> <ul id="toc-Senescence-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Ontogenetic_allometry" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Ontogenetic_allometry"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.9</span> <span>Ontogenetic allometry</span> </div> </a> <ul id="toc-Ontogenetic_allometry-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Notes_and_references" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Notes_and_references"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Notes and references</span> </div> </a> <ul id="toc-Notes_and_references-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Ontogeny</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 51 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-51" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">51 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%AA%D8%B7%D9%88%D8%B1_%D8%A7%D9%84%D8%AC%D9%86%D9%8A%D9%86" title="تطور الجنين – Arabic" lang="ar" hreflang="ar" data-title="تطور الجنين" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-ast mw-list-item"><a href="https://ast.wikipedia.org/wiki/Ontoxenia" title="Ontoxenia – Asturian" lang="ast" hreflang="ast" data-title="Ontoxenia" data-language-autonym="Asturianu" data-language-local-name="Asturian" class="interlanguage-link-target"><span>Asturianu</span></a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/Ontogenez" title="Ontogenez – Azerbaijani" lang="az" hreflang="az" data-title="Ontogenez" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/%D0%90%D0%BD%D1%82%D0%B0%D0%B3%D0%B5%D0%BD%D0%B5%D0%B7" title="Антагенез – Belarusian" lang="be" hreflang="be" data-title="Антагенез" data-language-autonym="Беларуская" data-language-local-name="Belarusian" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-be-x-old mw-list-item"><a href="https://be-tarask.wikipedia.org/wiki/%D0%9E%D0%BD%D1%82%D0%B0%D0%B3%D0%B5%D0%BD%D1%8D%D0%B7" title="Онтагенэз – Belarusian (Taraškievica orthography)" lang="be-tarask" hreflang="be-tarask" data-title="Онтагенэз" data-language-autonym="Беларуская (тарашкевіца)" data-language-local-name="Belarusian (Taraškievica orthography)" class="interlanguage-link-target"><span>Беларуская (тарашкевіца)</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%9E%D0%BD%D1%82%D0%BE%D0%B3%D0%B5%D0%BD%D0%B5%D0%B7%D0%B0" title="Онтогенеза – Bulgarian" lang="bg" hreflang="bg" data-title="Онтогенеза" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/Ontogeneza" title="Ontogeneza – Bosnian" lang="bs" hreflang="bs" data-title="Ontogeneza" data-language-autonym="Bosanski" data-language-local-name="Bosnian" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Ontog%C3%A8nia" title="Ontogènia – Catalan" lang="ca" hreflang="ca" data-title="Ontogènia" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Ontogeneze" title="Ontogeneze – Czech" lang="cs" hreflang="cs" data-title="Ontogeneze" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Ontogenese" title="Ontogenese – German" lang="de" hreflang="de" data-title="Ontogenese" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Ontogenees" title="Ontogenees – Estonian" lang="et" hreflang="et" data-title="Ontogenees" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Ontogenia" title="Ontogenia – Spanish" lang="es" hreflang="es" data-title="Ontogenia" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Individugenezo" title="Individugenezo – Esperanto" lang="eo" hreflang="eo" data-title="Individugenezo" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Ontogenia" title="Ontogenia – Basque" lang="eu" hreflang="eu" data-title="Ontogenia" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%A7%D9%88%D9%86%D8%AA%D9%88%DA%98%D9%86%DB%8C" title="اونتوژنی – Persian" lang="fa" hreflang="fa" data-title="اونتوژنی" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Ontogen%C3%A8se" title="Ontogenèse – French" lang="fr" hreflang="fr" data-title="Ontogenèse" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Ontoxenia" title="Ontoxenia – Galician" lang="gl" hreflang="gl" data-title="Ontoxenia" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-inh mw-list-item"><a href="https://inh.wikipedia.org/wiki/%D0%9E%D0%BD%D1%82%D0%BE%D0%B3%D0%B5%D0%BD%D0%B5%D0%B7" title="Онтогенез – Ingush" lang="inh" hreflang="inh" data-title="Онтогенез" data-language-autonym="ГӀалгӀай" data-language-local-name="Ingush" class="interlanguage-link-target"><span>ГӀалгӀай</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D5%95%D5%B6%D5%BF%D5%B8%D5%A3%D5%A5%D5%B6%D5%A5%D5%A6" title="Օնտոգենեզ – Armenian" lang="hy" hreflang="hy" data-title="Օնտոգենեզ" data-language-autonym="Հայերեն" data-language-local-name="Armenian" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Ontogeni" title="Ontogeni – Indonesian" lang="id" hreflang="id" data-title="Ontogeni" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Ontogenesi" title="Ontogenesi – Italian" lang="it" hreflang="it" data-title="Ontogenesi" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-ka mw-list-item"><a href="https://ka.wikipedia.org/wiki/%E1%83%9D%E1%83%9C%E1%83%A2%E1%83%9D%E1%83%92%E1%83%94%E1%83%9C%E1%83%94%E1%83%96%E1%83%98" title="ონტოგენეზი – Georgian" lang="ka" hreflang="ka" data-title="ონტოგენეზი" data-language-autonym="ქართული" data-language-local-name="Georgian" class="interlanguage-link-target"><span>ქართული</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%9E%D0%BD%D1%82%D0%BE%D0%B3%D0%B5%D0%BD%D0%B5%D0%B7" title="Онтогенез – Kazakh" lang="kk" hreflang="kk" data-title="Онтогенез" data-language-autonym="Қазақша" data-language-local-name="Kazakh" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-ky mw-list-item"><a href="https://ky.wikipedia.org/wiki/%D0%9E%D0%BD%D1%82%D0%BE%D0%B3%D0%B5%D0%BD%D0%B5%D0%B7" title="Онтогенез – Kyrgyz" lang="ky" hreflang="ky" data-title="Онтогенез" data-language-autonym="Кыргызча" data-language-local-name="Kyrgyz" class="interlanguage-link-target"><span>Кыргызча</span></a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/Onto%C4%A3en%C4%93ze" title="Ontoģenēze – Latvian" lang="lv" hreflang="lv" data-title="Ontoģenēze" data-language-autonym="Latviešu" data-language-local-name="Latvian" class="interlanguage-link-target"><span>Latviešu</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Egyedfejl%C5%91d%C3%A9s" title="Egyedfejlődés – Hungarian" lang="hu" hreflang="hu" data-title="Egyedfejlődés" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%9E%D0%BD%D1%82%D0%BE%D0%B3%D0%B5%D0%BD%D0%B5%D0%B7%D0%B0" title="Онтогенеза – Macedonian" lang="mk" hreflang="mk" data-title="Онтогенеза" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Ontwikkelingsfysiologie" title="Ontwikkelingsfysiologie – Dutch" lang="nl" hreflang="nl" data-title="Ontwikkelingsfysiologie" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja badge-Q70893996 mw-list-item" title=""><a href="https://ja.wikipedia.org/wiki/%E5%80%8B%E4%BD%93%E7%99%BA%E7%94%9F" title="個体発生 – Japanese" lang="ja" hreflang="ja" data-title="個体発生" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Ontogenese" title="Ontogenese – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Ontogenese" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-uz mw-list-item"><a href="https://uz.wikipedia.org/wiki/Ontogenez" title="Ontogenez – Uzbek" lang="uz" hreflang="uz" data-title="Ontogenez" data-language-autonym="Oʻzbekcha / ўзбекча" data-language-local-name="Uzbek" class="interlanguage-link-target"><span>Oʻzbekcha / ўзбекча</span></a></li><li class="interlanguage-link interwiki-nds mw-list-item"><a href="https://nds.wikipedia.org/wiki/Ontogenese" title="Ontogenese – Low German" lang="nds" hreflang="nds" data-title="Ontogenese" data-language-autonym="Plattdüütsch" data-language-local-name="Low German" class="interlanguage-link-target"><span>Plattdüütsch</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Ontogeneza" title="Ontogeneza – Polish" lang="pl" hreflang="pl" data-title="Ontogeneza" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Ontogenia" title="Ontogenia – Portuguese" lang="pt" hreflang="pt" data-title="Ontogenia" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-kaa mw-list-item"><a href="https://kaa.wikipedia.org/wiki/Ontogenez" title="Ontogenez – Kara-Kalpak" lang="kaa" hreflang="kaa" data-title="Ontogenez" data-language-autonym="Qaraqalpaqsha" data-language-local-name="Kara-Kalpak" class="interlanguage-link-target"><span>Qaraqalpaqsha</span></a></li><li class="interlanguage-link interwiki-rue mw-list-item"><a href="https://rue.wikipedia.org/wiki/%D0%9E%D0%BD%D1%82%D0%BE%D0%B3%D0%B5%D0%BD%D0%B5%D0%B7%D0%B0" title="Онтогенеза – Rusyn" lang="rue" hreflang="rue" data-title="Онтогенеза" data-language-autonym="Русиньскый" data-language-local-name="Rusyn" class="interlanguage-link-target"><span>Русиньскый</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9E%D0%BD%D1%82%D0%BE%D0%B3%D0%B5%D0%BD%D0%B5%D0%B7" title="Онтогенез – Russian" lang="ru" hreflang="ru" data-title="Онтогенез" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sc mw-list-item"><a href="https://sc.wikipedia.org/wiki/Ontog%C3%A8nesi" title="Ontogènesi – Sardinian" lang="sc" hreflang="sc" data-title="Ontogènesi" data-language-autonym="Sardu" data-language-local-name="Sardinian" class="interlanguage-link-target"><span>Sardu</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Ontogen%C3%A9za" title="Ontogenéza – Slovak" lang="sk" hreflang="sk" data-title="Ontogenéza" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Ontogenija" title="Ontogenija – Slovenian" lang="sl" hreflang="sl" data-title="Ontogenija" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%9E%D0%BD%D1%82%D0%BE%D0%B3%D0%B5%D0%BD%D0%B5%D1%82%D1%81%D0%BA%D0%BE_%D1%80%D0%B0%D0%B7%D0%B2%D0%B8%D1%9B%D0%B5" title="Онтогенетско развиће – Serbian" lang="sr" hreflang="sr" data-title="Онтогенетско развиће" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Ontogenetsko_razvi%C4%87e" title="Ontogenetsko razviće – Serbo-Croatian" lang="sh" hreflang="sh" data-title="Ontogenetsko razviće" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Yksil%C3%B6nkehitys" title="Yksilönkehitys – Finnish" lang="fi" hreflang="fi" data-title="Yksilönkehitys" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Ontogeni" title="Ontogeni – Swedish" lang="sv" hreflang="sv" data-title="Ontogeni" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-tt mw-list-item"><a href="https://tt.wikipedia.org/wiki/%D0%9E%D0%BD%D1%82%D0%BE%D0%B3%D0%B5%D0%BD%D0%B5%D0%B7" title="Онтогенез – Tatar" lang="tt" hreflang="tt" data-title="Онтогенез" data-language-autonym="Татарча / tatarça" data-language-local-name="Tatar" class="interlanguage-link-target"><span>Татарча / tatarça</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Ontojeni" title="Ontojeni – Turkish" lang="tr" hreflang="tr" data-title="Ontojeni" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%9E%D0%BD%D1%82%D0%BE%D0%B3%D0%B5%D0%BD%D0%B5%D0%B7" title="Онтогенез – Ukrainian" lang="uk" hreflang="uk" data-title="Онтогенез" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li 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id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Origination and development of an organism</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">This article concerns ontogeny in biology. Not to be confused with the philosophical concept <a href="/wiki/Ontology" title="Ontology">ontology</a>, or the medical terms <a href="/wiki/Oncology" title="Oncology">oncology</a> or <a href="/wiki/Odontology" class="mw-redirect" title="Odontology">odontology</a>.</div> <p class="mw-empty-elt"> </p> <figure typeof="mw:File/Thumb"><a href="/wiki/File:HumanEmbryogenesis.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/06/HumanEmbryogenesis.svg/300px-HumanEmbryogenesis.svg.png" decoding="async" width="300" height="235" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/06/HumanEmbryogenesis.svg/450px-HumanEmbryogenesis.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/06/HumanEmbryogenesis.svg/600px-HumanEmbryogenesis.svg.png 2x" data-file-width="1560" data-file-height="1220" /></a><figcaption>The initial stages of <a href="/wiki/Human_embryogenesis" class="mw-redirect" title="Human embryogenesis">human embryogenesis</a></figcaption></figure> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Human_embryo_8_weeks_2.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Human_embryo_8_weeks_2.JPG/300px-Human_embryo_8_weeks_2.JPG" decoding="async" width="300" height="225" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Human_embryo_8_weeks_2.JPG/450px-Human_embryo_8_weeks_2.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Human_embryo_8_weeks_2.JPG/600px-Human_embryo_8_weeks_2.JPG 2x" data-file-width="960" data-file-height="720" /></a><figcaption>Parts of a human embryo</figcaption></figure> <p><b>Ontogeny</b> (also <b>ontogenesis</b>) is the origination and development of an <a href="/wiki/Organism" title="Organism">organism</a> (both physical and psychological, e.g., moral development<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup>), usually from the time of <a href="/wiki/Fertilization" class="mw-redirect" title="Fertilization">fertilization</a> of the <a href="/wiki/Ovum" class="mw-redirect" title="Ovum">egg</a> to adult. The term can also be used to refer to the study of the entirety of an organism's lifespan. </p><p>Ontogeny is the developmental history of an organism within its own lifetime, as distinct from <a href="/wiki/Phylogeny" class="mw-redirect" title="Phylogeny">phylogeny</a>, which refers to the <a href="/wiki/Evolution" title="Evolution">evolutionary</a> history of a species. Another way to think of ontogeny is that it is the process of an organism going through all of the developmental stages over its lifetime. The developmental history includes all the developmental events that occur during the existence of an organism, beginning with the changes in the egg at the time of fertilization and events from the time of birth or hatching and afterward (i.e., growth, remolding of body shape, development of secondary sexual characteristics, etc.).<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> While developmental (i.e., ontogenetic) processes can influence subsequent evolutionary (e.g., phylogenetic) processes<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> (see <a href="/wiki/Evolutionary_developmental_biology" title="Evolutionary developmental biology">evolutionary developmental biology</a> and <a href="/wiki/Recapitulation_theory" title="Recapitulation theory">recapitulation theory</a>), individual organisms develop (ontogeny), while species evolve (phylogeny). </p><p>Ontogeny, <a href="/wiki/Embryology" title="Embryology">embryology</a> and <a href="/wiki/Developmental_biology" title="Developmental biology">developmental biology</a> are closely related studies and those terms are sometimes used interchangeably. Aspects of ontogeny are <a href="/wiki/Morphogenesis" title="Morphogenesis">morphogenesis</a>, the development of form and shape of an organism; tissue growth; and <a href="/wiki/Cellular_differentiation" title="Cellular differentiation">cellular differentiation</a>. The term ontogeny has also been used in <a href="/wiki/Cell_biology" title="Cell biology">cell biology</a> to describe the development of various <a href="/wiki/Cell_types" class="mw-redirect" title="Cell types">cell types</a> within an organism.<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> Ontogeny is a useful field of study in many disciplines, including <a href="/wiki/Developmental_biology" title="Developmental biology">developmental biology</a>, <a href="/wiki/Cell_biology" title="Cell biology">cell biology</a>, <a href="/wiki/Genetics" title="Genetics">genetics</a>, <a href="/wiki/Developmental_psychology" title="Developmental psychology">developmental psychology</a>, <a href="/wiki/Developmental_cognitive_neuroscience" title="Developmental cognitive neuroscience">developmental cognitive neuroscience</a>, and <a href="/wiki/Developmental_psychobiology" title="Developmental psychobiology">developmental psychobiology</a>. Ontogeny is used in <a href="/wiki/Anthropology" title="Anthropology">anthropology</a> as "the process through which each of us embodies the history of our own making".<sup id="cite_ref-Toren,_Christina_2002_5-0" class="reference"><a href="#cite_note-Toren,_Christina_2002-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Etymology">Etymology</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=1" title="Edit section: Etymology"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The word <i>ontogeny</i> comes from the <a href="/wiki/Ancient_Greek" title="Ancient Greek">Greek</a> <i>on</i> meaning a being, individual; and existence, and from the suffix <i>-geny</i> from the Greek -<i>geniea</i>, meaning genesis, origin, and mode of production.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=2" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The term ontogeny was coined by <a href="/wiki/Ernst_Haeckel" title="Ernst Haeckel">Ernst Haeckel</a>, a German zoologist and evolutionist in the 1860s. Haeckel, born in Germany on February 16, 1834, was also a strong supporter of <a href="/wiki/Darwinism" title="Darwinism">Darwinism</a>. Haeckel suggested that ontogeny briefly and sometimes incompletely recapitulated or repeated phylogeny in his 1866 book, <i>Generelle Morphologie der Organismen</i> ("General Morphology of Organisms"). Even though his book was widely read, the scientific community was not very convinced or interested in his ideas, so he turned to producing more publications to get more attention.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> In 1866, Haeckel and others imagined development as producing new structures after earlier additions to the developing organism have been established. He proposed that individual development followed developmental stages of previous generations and that the future generations would add something new to this process, and that there was a causal parallelism between an animal's ontogeny and phylogeny. In addition, Haeckel suggested a biogenetic law that ontogeny recapitulates phylogeny, based on the idea that the successive and progressive origin of new species was based on the same laws as the successive and progressive origin of new embryonic structures. According to Haeckel, development produced novelties, and natural selection would eliminate species that had become outdated or obsolete. Though his view of development and evolution wasn't justifiable, future embryologists tweaked and collaborated with Haeckel's proposals and showed how new morphological structures can occur by the hereditary modification of embryonic development.<sup id="cite_ref-Gilbert-2015_8-0" class="reference"><a href="#cite_note-Gilbert-2015-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> Marine biologist <a href="/wiki/Walter_Garstang" title="Walter Garstang">Walter Garstang</a> reversed Haeckel's relationship between ontogeny and phylogeny, stating that ontogeny creates phylogeny, not recapitulates it.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p><p>A seminal 1963 paper by <a href="/wiki/Nikolaas_Tinbergen" title="Nikolaas Tinbergen">Nikolaas Tinbergen</a> named ontogeny as one of the <a href="/wiki/Tinbergen%27s_four_questions" title="Tinbergen's four questions">four primary questions</a> of biology, along with <a href="/wiki/Julian_Huxley" title="Julian Huxley">Julian Huxley's</a> three others: causation, survival value and evolution.<sup id="cite_ref-Tinbergen_11-0" class="reference"><a href="#cite_note-Tinbergen-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> Tinbergen emphasized that the change of behavioral <i>machinery</i> during development was distinct from the change in behavior during development. We can conclude that the thrush itself, i.e. its behavioral machinery, has changed only if the behavior change occurred while the environment was held constant...When we turn from description to causal analysis, and ask in what way the observed change in behavior machinery has been brought about, the natural first step is to try and distinguish between environmental influences and those within the animal...In ontogeny the conclusion that a certain change is internally controlled (is 'innate') is reached by <i>elimination</i>.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> Tinbergen was concerned that the elimination of environmental factors is difficult to establish, and the use of the word innate is often misleading. </p> <div class="mw-heading mw-heading2"><h2 id="Developmental_stages">Developmental stages</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=3" title="Edit section: Developmental stages"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Development of an organism happens through fertilization, cleavage, blastulation, gastrulation, organogenesis, and metamorphosis into an adult. Each species of <a href="/wiki/Animal" title="Animal">animal</a> has a slightly different journey through these stages, since some stages might be shorter or longer when compared to other species, and where the offspring develops is different for each animal type (e.g., in a hard egg shell, uterus, soft egg shell, on a plant leaf, etc.).<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Fertilization">Fertilization</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=4" title="Edit section: Fertilization"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In humans, the process of <a href="/wiki/Prenatal_development" title="Prenatal development">fetal development</a> starts after <a href="/wiki/Sperm" title="Sperm">sperm</a> fertilizes an <a href="/wiki/Egg_cell" title="Egg cell">egg</a> and they fuse together, kickstarting <a href="/wiki/Embryo" title="Embryo">embryonic development</a>. The fusion of egg and sperm into a <a href="/wiki/Zygote" title="Zygote">zygote</a> changes the surrounding membrane to not allow any more sperm to penetrate the egg, so multiple fertilizations can be prevented. Fusion of a zygote also activates the egg so it can begin undergoing cell division. Each animal <a href="/wiki/Species" title="Species">species</a> might not have specifically a sperm and an egg, but two gametes that contain half of the species' typical genetic material and the membranes of these gametes fuse to start creating an offspring.<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Cleavage">Cleavage</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=5" title="Edit section: Cleavage"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Not long after successful fertilization by sperm, the zygote undergoes many <a href="/wiki/Mitosis" title="Mitosis">mitotic divisions</a>, which are also non-sexual cell divisions. <a href="/wiki/Cleavage_(embryo)" title="Cleavage (embryo)">Cleavage</a> is the process of cell division, so the starting zygote becomes a collection of identical cells which is a morula and contains cells called blastomeres.<sup id="cite_ref-Muhr-2022_15-0" class="reference"><a href="#cite_note-Muhr-2022-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> Cleavage prepares the zygote to become an embryo, which is from 2 weeks to 8 weeks after conception (fertilization) in humans.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> </p> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Figure_27_01_03.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4d/Figure_27_01_03.jpg/590px-Figure_27_01_03.jpg" decoding="async" width="590" height="198" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/4/4d/Figure_27_01_03.jpg 1.5x" data-file-width="800" data-file-height="268" /></a><figcaption>Process of zygote to gastrula in development</figcaption></figure> <div class="mw-heading mw-heading3"><h3 id="Blastulation">Blastulation</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=6" title="Edit section: Blastulation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>After the zygote has become an embryo, it continues dividing into a hollow sphere of cells, which is a <a href="/wiki/Blastulation" title="Blastulation">blastula</a>. These outer cells form a single epithelial layer, the blastoderm, that essentially encases the fluid-filled inside that is the blastocoel. The figure to the right shows the basic process that is modified in different species. Blastulation differs slightly in different species, but in mammals, the eight-cell stage embryo forms into a slightly different type of blastula, called a blastocyst.<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> Other species such as <a href="/wiki/Starfish" title="Starfish">sea stars</a>, <a href="/wiki/Frog" title="Frog">frogs</a>, <a href="/wiki/Chicken" title="Chicken">chicks</a>, and <a href="/wiki/Mouse" title="Mouse">mice</a> have all the same structures in this stage, yet the orientation of these features differs, plus these species have additional types of cells in this stage.<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> </p> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Blastula.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d9/Blastula.png/457px-Blastula.png" decoding="async" width="457" height="240" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/d9/Blastula.png/686px-Blastula.png 1.5x, //upload.wikimedia.org/wikipedia/commons/d/d9/Blastula.png 2x" data-file-width="707" data-file-height="371" /></a><figcaption>Blastula to gastrula more detailed</figcaption></figure> <div class="mw-heading mw-heading3"><h3 id="Gastrulation">Gastrulation</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=7" title="Edit section: Gastrulation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>After blastulation, the single-layered blastula expands and reorganizes into multiple layers, a gastrula (seen in the figure to the right). <a href="/wiki/Reptile" title="Reptile">Reptiles</a>, <a href="/wiki/Bird" title="Bird">birds</a> and <a href="/wiki/Mammal" title="Mammal">mammals</a> are triploblastic organisms, meaning the gastrula comprises three <a href="/wiki/Germ_layer" title="Germ layer">germ layers</a>; the endoderm (inner layer), mesoderm (middle layer), and ectoderm (outer layer).<sup id="cite_ref-Muhr-2022_15-1" class="reference"><a href="#cite_note-Muhr-2022-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> As seen in the figure below, each germ layer will become <a href="/wiki/Cell_potency" title="Cell potency">multi-potent stem cells</a> that can become a specific tissue depending on the germ layer and is what happens in humans. This <a href="/wiki/Cellular_differentiation" title="Cellular differentiation">differentiation</a> of germ layers differs slightly, because not all of the organs and tissues below are in all organisms, but corresponding body systems can be substituted in place of these.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Organogenesis">Organogenesis</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=8" title="Edit section: Organogenesis"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In the figure below, human germ cells are able to differentiate into the specific organs and tissues they become later on in life. Germ cells are able to migrate to their final locations to rearrange themselves and some organs are made of two germ layers; one for the outside, the other for the inside.<sup id="cite_ref-Gilbert-2000-2_20-0" class="reference"><a href="#cite_note-Gilbert-2000-2-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> The <a href="/wiki/Endoderm" title="Endoderm">endoderm</a> cells become the internal linings of organisms, such as the stomach, colon, small intestine, liver, and pancreas of the digestive system and the lungs. The <a href="/wiki/Mesoderm" title="Mesoderm">mesoderm</a> gives rise to other tissues not formed by the ectoderm, such as the heart, muscles, bones, blood, dermis of the skin, bone marrow, and the urogenital system. This germ layer is more specific for species, as it is the distinguishing layer of the three that can identify evolutionarily higher life-forms (e.g., bilateral organisms like humans) from lower-life forms (with radial symmetry). Lastly, the <a href="/wiki/Ectoderm" title="Ectoderm">ectoderm</a> is the outer layer of cells that become the <a href="/wiki/Epidermis" title="Epidermis">epidermis</a> and hair while being the precursor to the mammary glands, <a href="/wiki/Central_nervous_system" title="Central nervous system">central nervous system</a>, and the <a href="/wiki/Peripheral_nervous_system" title="Peripheral nervous system">peripheral nervous systems</a>.<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-halign-center" typeof="mw:File/Thumb"><a href="/wiki/File:Germ_layers.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/52/Germ_layers.jpg/900px-Germ_layers.jpg" decoding="async" width="900" height="213" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/5/52/Germ_layers.jpg 1.5x" data-file-width="1117" data-file-height="264" /></a><figcaption>Germ layers and what tissues they become in humans</figcaption></figure> <figure class="mw-halign-center" typeof="mw:File/Thumb"><a href="/wiki/File:Ernst_Haeckel,_Anthropogenie._Wellcome_L0027291.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1e/Ernst_Haeckel%2C_Anthropogenie._Wellcome_L0027291.jpg/340px-Ernst_Haeckel%2C_Anthropogenie._Wellcome_L0027291.jpg" decoding="async" width="340" height="529" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1e/Ernst_Haeckel%2C_Anthropogenie._Wellcome_L0027291.jpg/510px-Ernst_Haeckel%2C_Anthropogenie._Wellcome_L0027291.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/1e/Ernst_Haeckel%2C_Anthropogenie._Wellcome_L0027291.jpg/679px-Ernst_Haeckel%2C_Anthropogenie._Wellcome_L0027291.jpg 2x" data-file-width="1102" data-file-height="1716" /></a><figcaption>Ernst Haeckel, Anthropogenie. </figcaption></figure><p> The figure above shows how the development of a <a href="/wiki/Pig" title="Pig">pig</a>, <a href="/wiki/Cattle" title="Cattle">cow</a>, <a href="/wiki/Rabbit" title="Rabbit">rabbit</a>, and <a href="/wiki/Human" title="Human">human</a> offspring are similar when compared to one another. This figure shows how the germ layers can become different organs and tissues in evolutionarily higher life-forms and how these species essentially develop very similarly. Additionally, it shows how multiple species develop in a parallel manner but branch off to develop more specific features for the organism such as hooves, a tail, or ears. </p><figure typeof="mw:File/Thumb"><a href="/wiki/File:2912_Neurulation-02.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/0f/2912_Neurulation-02.jpg/505px-2912_Neurulation-02.jpg" decoding="async" width="505" height="583" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/0f/2912_Neurulation-02.jpg/757px-2912_Neurulation-02.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/0f/2912_Neurulation-02.jpg/1009px-2912_Neurulation-02.jpg 2x" data-file-width="1952" data-file-height="2255" /></a><figcaption>Primary neurulation detailed</figcaption></figure> <div class="mw-heading mw-heading4"><h4 id="Neurulation">Neurulation</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=9" title="Edit section: Neurulation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In developing <a href="/wiki/Vertebrate" title="Vertebrate">vertebrate</a> offspring, a <a href="/wiki/Neural_tube" title="Neural tube">neural tube</a> is formed through either <a href="/wiki/Neurulation" title="Neurulation">primary or secondary neurulation</a>. Some species develop their spine and nervous system using both primary and secondary neurulation, while others use only primary or secondary neurulation.<sup id="cite_ref-Gilbert-2000_22-0" class="reference"><a href="#cite_note-Gilbert-2000-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> In human fetal development, primary neurulation occurs during weeks 3 and 4 of gestation to develop the brain and spinal cord. Then during weeks 5 and 6 of gestation, secondary neurulation forms the lower sacral and coccygeal cord.<sup id="cite_ref-www.sciencedirect.com_23-0" class="reference"><a href="#cite_note-www.sciencedirect.com-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading5"><h5 id="Primary_Neurulation">Primary Neurulation</h5><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=10" title="Edit section: Primary Neurulation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The diagram to the right illustrates primary neurulation, which is the process of cells surrounding the neural plate interacting with neural plate cells to proliferate, converge, and pinch off to form a hollow tube above the <a href="/wiki/Notochord" title="Notochord">notochord</a> and mesoderm. This process is discontinuous and can start at different points along the cranial-caudal axis necessary for it to close.<sup id="cite_ref-www.sciencedirect.com_23-1" class="reference"><a href="#cite_note-www.sciencedirect.com-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> After the neural crest closes, the neural crest cells and ectoderm cells separate and the ectoderm becomes the epidermis surrounding this complex. The neural crest cells differentiate to become components of most of the peripheral nervous system in animals. Next, the notochord degenerates to become only the <a href="/wiki/Intervertebral_disc" title="Intervertebral disc">nucleus pulposus</a> of the <a href="/wiki/Intervertebral_disc" title="Intervertebral disc">intervertebral discs</a> and the mesoderm cells differentiate to become the <a href="/wiki/Somite" title="Somite">somites</a> and skeletal muscle later on. Also during this stage, the neural crest cells become the spinal ganglions, which function as the brain in organisms like <a href="/wiki/Earthworm" title="Earthworm">earthworms</a> and <a href="/wiki/Arthropod" title="Arthropod">arthropods</a>.<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> In more advanced organisms like <a href="/wiki/Amphibian" title="Amphibian">amphibians</a>, <a href="/wiki/Bird" title="Bird">birds</a> and <a href="/wiki/Mammal" title="Mammal">mammals</a>;<sup id="cite_ref-Gilbert-2000_22-1" class="reference"><a href="#cite_note-Gilbert-2000-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> the spinal ganglions consists of a cluster of nerve bodies positioned along the spinal cord at the dorsal and ventral roots of a spinal nerve, which is a pair of nerves that correspond to a vertebra of the spine.<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading5"><h5 id="Secondary_Neurulation">Secondary Neurulation</h5><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=11" title="Edit section: Secondary Neurulation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In secondary neurulation, caudal and sacral regions of the spine are formed after primary neurulation is finished. This process initiates once primary neurulation is finished and the posterior neuropore closes, so the tail bud can proliferate and condense, then create a cavity and fuse with the central canal of the neural tube. Secondary neurulation occurs in the small region starting at the <a href="/wiki/Tail_bud" class="mw-redirect" title="Tail bud">spinal tail bud</a> up to the posterior neuropore, which is the open neural folds near the tail region that don't close through primary neurulation. As canalization progresses over the next few weeks, neurons and ependymal cells (cells that create cerebral spinal fluid<sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup>) differentiate to become the tail end of the spinal cord. Next, the closed neural tube contains neuroepithelial cells that immediately divide after closure and a second type of cell forms; the neuroblast. <a href="/wiki/Neuroblast" title="Neuroblast">Neuroblast</a> cells form the mantle layer, which later becomes the <a href="/wiki/Grey_matter" title="Grey matter">gray matter</a>, which then gives rise to a marginal layer that becomes the <a href="/wiki/White_matter" title="White matter">white matter</a> of the spinal cord.<sup id="cite_ref-www.sciencedirect.com_23-2" class="reference"><a href="#cite_note-www.sciencedirect.com-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> Secondary neurulation is seen in the neural tube of the lumbar and tail vertebrae of <a href="/wiki/Frog" title="Frog">frogs</a> and <a href="/wiki/Chicken" title="Chicken">chicks</a> and in both instances, this process is like a continuation of gastrulation.<sup id="cite_ref-Gilbert-2000_22-2" class="reference"><a href="#cite_note-Gilbert-2000-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Acraea_zetes_caterpillar_to_pupae_to_butterfly_metamorphosis_by_Nick_Hobgood.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/59/Acraea_zetes_caterpillar_to_pupae_to_butterfly_metamorphosis_by_Nick_Hobgood.jpg/220px-Acraea_zetes_caterpillar_to_pupae_to_butterfly_metamorphosis_by_Nick_Hobgood.jpg" decoding="async" width="220" height="513" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/59/Acraea_zetes_caterpillar_to_pupae_to_butterfly_metamorphosis_by_Nick_Hobgood.jpg/330px-Acraea_zetes_caterpillar_to_pupae_to_butterfly_metamorphosis_by_Nick_Hobgood.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/59/Acraea_zetes_caterpillar_to_pupae_to_butterfly_metamorphosis_by_Nick_Hobgood.jpg/440px-Acraea_zetes_caterpillar_to_pupae_to_butterfly_metamorphosis_by_Nick_Hobgood.jpg 2x" data-file-width="1200" data-file-height="2800" /></a><figcaption>Acraea zetes caterpillar to pupae to butterfly metamorphosis by Nick Hobgood</figcaption></figure> <div class="mw-heading mw-heading3"><h3 id="Larval_and_juvenile_phases">Larval and juvenile phases</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=12" title="Edit section: Larval and juvenile phases"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In most species, the young organism that is just born or hatched is not sexually mature yet and in most animals, this young organism looks quite different than the adult form.<sup id="cite_ref-Gilbert-2000-2_20-1" class="reference"><a href="#cite_note-Gilbert-2000-2-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> This young organism is the larva and is the intermediate form before <a href="/wiki/Metamorphosis" title="Metamorphosis">metamorphosing</a> into an adult.<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Gilbert-2015_8-1" class="reference"><a href="#cite_note-Gilbert-2015-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> A well known example of a larval form of an animal is the <a href="/wiki/Caterpillar" title="Caterpillar">caterpillar</a> of <a href="/wiki/Butterfly" title="Butterfly">butterflies</a> and <a href="/wiki/Moth" title="Moth">moths</a>. Caterpillars keep growing and feeding in order for enough energy during the pupal stage, when necessary body parts for <a href="/wiki/Metamorphosis" title="Metamorphosis">metamorphosis</a> are grown.<sup id="cite_ref-28" class="reference"><a href="#cite_note-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> The juvenile phase is different in plants and animals, but in plants juvenility is an early phase of plant growth in which plants can't flower.<sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> In animals, the juvenile stage is most commonly found in social mammals, such as <a href="/wiki/Dingo" title="Dingo">wild dogs</a>, <a href="/wiki/Monkey" title="Monkey">monkeys</a>, <a href="/wiki/Ape" title="Ape">apes</a>, <a href="/wiki/Lion" title="Lion">lions</a>, <a href="/wiki/Wolf" title="Wolf">wolves</a>, and more. In humans, <a href="/wiki/Puberty" title="Puberty">puberty</a> marks the end of this stage and <a href="/wiki/Adolescence" title="Adolescence">adolescence</a> follows. Some species begin puberty and reproduction before the juvenile stage is over, such as in female non-human primates.<sup id="cite_ref-30" class="reference"><a href="#cite_note-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> The larval and pupal stages can be seen in the figure to the right. </p> <div class="mw-heading mw-heading3"><h3 id="Metamorphosis">Metamorphosis</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=13" title="Edit section: Metamorphosis"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The process of an organism's body undergoing structural and physical changes after birth or hatching to become suitable for its adult environment is <a href="/wiki/Metamorphosis" title="Metamorphosis">metamorphosis</a>.<sup id="cite_ref-Britannica_31-0" class="reference"><a href="#cite_note-Britannica-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> For example, <a href="/wiki/Amphibian" title="Amphibian">amphibian</a> tadpoles have a maturation of liver enzymes, <a href="/wiki/Hemoglobin" title="Hemoglobin">hemoglobin</a>, and eye pigments, in addition to their nervous, digestive, and reproductive systems being remodeled.<sup id="cite_ref-32" class="reference"><a href="#cite_note-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> In all species, <a href="/wiki/Moulting" title="Moulting">molting</a> and <a href="/wiki/Juvenile_hormone" title="Juvenile hormone">juvenile hormones</a> appear to regulate these changes.<sup id="cite_ref-Britannica_31-1" class="reference"><a href="#cite_note-Britannica-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> The figure to the right shows the stages of life in butterflies and their metamorphosis transforms the caterpillar into a butterfly. </p> <div class="mw-heading mw-heading3"><h3 id="Adulthood">Adulthood</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=14" title="Edit section: Adulthood"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Adult" title="Adult">Adulthood</a> is the stage of when physical and intellectual maturity have been achieved and this differs between species. In <a href="/wiki/Human_development_(biology)" class="mw-redirect" title="Human development (biology)">humans</a>, adulthood is thought to be around 20 or 21 years old and is the longest stage of life, but in all species it ends with death.<sup id="cite_ref-33" class="reference"><a href="#cite_note-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> In <a href="/wiki/Dog" title="Dog">dogs</a>, small breeds (e.g., <a href="/wiki/Yorkshire_Terrier" title="Yorkshire Terrier">Yorkshire Terrier</a>, <a href="/wiki/Chihuahua_(dog)" class="mw-redirect" title="Chihuahua (dog)">Chihuahua</a>, <a href="/wiki/Cocker_Spaniel" title="Cocker Spaniel">Cocker Spaniel</a>, etc.) physically mature faster than large breeds (e.g., <a href="/wiki/St._Bernard_(dog)" class="mw-redirect" title="St. Bernard (dog)">Saint Bernard</a>, <a href="/wiki/Great_Dane" title="Great Dane">Great Dane</a>, <a href="/wiki/Golden_Retriever" title="Golden Retriever">Golden Retriever</a>, etc.), so adulthood is reached anywhere from 12 to 24 months or 1 to 2 years.<sup id="cite_ref-34" class="reference"><a href="#cite_note-34"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> In contrast, many insect species have long larval stages and the adult stage is only for reproduction. The silkworm <a href="/wiki/Moth" title="Moth">moths</a> don't have mouthparts and don't feed, so they have to consume enough food during the larval stage for energy to survive and mate.<sup id="cite_ref-Gilbert-2000-2_20-2" class="reference"><a href="#cite_note-Gilbert-2000-2-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="Senescence">Senescence</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=15" title="Edit section: Senescence"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Senescence" title="Senescence">Senescence</a> is when cells stop dividing but don't die, but these cells can build up and cause problems in the body. These cells can release substances that cause inflammation and can damage healthy nearby cells.<sup id="cite_ref-35" class="reference"><a href="#cite_note-35"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> Senescence can be induced by un-repaired DNA damage (e.g., from radiation,<sup id="cite_ref-36" class="reference"><a href="#cite_note-36"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> old age, etc.) or other cellular stress<sup id="cite_ref-37" class="reference"><a href="#cite_note-37"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup> and also is the state of being old.<sup id="cite_ref-38" class="reference"><a href="#cite_note-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Ontogenetic_allometry">Ontogenetic allometry</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=16" title="Edit section: Ontogenetic allometry"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Most organisms undergo <a href="/wiki/Allometry" title="Allometry">allometric</a> changes in <a href="/wiki/Shape" title="Shape">shape</a> as they grow and <a href="/wiki/Developmental_biology" title="Developmental biology">mature</a>, while others engage in <a href="/wiki/Metamorphosis" title="Metamorphosis">metamorphosis</a>. Even reptiles (non-avian sauropsids, e.g., <a href="/wiki/Crocodilians" class="mw-redirect" title="Crocodilians">crocodilians</a>, <a href="/wiki/Turtles" class="mw-redirect" title="Turtles">turtles</a>, <a href="/wiki/Snakes" class="mw-redirect" title="Snakes">snakes</a>,<sup id="cite_ref-39" class="reference"><a href="#cite_note-39"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> and <a href="/wiki/Lizards" class="mw-redirect" title="Lizards">lizards</a><sup id="cite_ref-40" class="reference"><a href="#cite_note-40"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup>), in which the offspring are often viewed as miniature adults, show a variety of ontogenetic changes in <a href="/wiki/Morphology_(biology)" title="Morphology (biology)">morphology</a> and <a href="/wiki/Physiology" title="Physiology">physiology</a>.<sup id="cite_ref-41" class="reference"><a href="#cite_note-41"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=17" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Developmental_biology" title="Developmental biology">Developmental biology</a></li> <li><a href="/wiki/Ernst_Haeckel" title="Ernst Haeckel">Ernst Haeckel</a></li> <li><a href="/wiki/Genetics" title="Genetics">Genetics</a></li> <li><a href="/wiki/Recapitulation_theory" title="Recapitulation theory">Recapitulation theory</a>, the idea that ontogeny recapitulates <a href="/wiki/Phylogeny" class="mw-redirect" title="Phylogeny">phylogeny</a></li> <li><a href="/wiki/Embryology" title="Embryology">Embryology</a></li> <li><a href="/wiki/Organogenesis" title="Organogenesis">Organogenesis</a></li> <li><a href="/wiki/Ontogeny_(psychoanalysis)" title="Ontogeny (psychoanalysis)">Ontogeny (psychoanalysis)</a></li> <li><a href="/wiki/Phylogenetics" title="Phylogenetics">Phylogenetics</a></li> <li><a href="/wiki/Phylogeny_(psychoanalysis)" title="Phylogeny (psychoanalysis)">Phylogeny (psychoanalysis)</a></li> <li><a href="/wiki/Apoptosis" title="Apoptosis">Apoptosis</a></li> <li><a href="/wiki/Evolutionary_developmental_biology" title="Evolutionary developmental biology">Evo-devo</a> (evolutionary developmental biology)</li> <li><a href="/wiki/Cellular_differentiation" title="Cellular differentiation">Cellular differentiation</a></li> <li><a href="/wiki/Cell_biology" title="Cell biology">Cell biology</a></li> <li><a href="/wiki/Nikolaas_Tinbergen" title="Nikolaas Tinbergen">Nikolaas Tinbergen</a></li> <li><a href="/wiki/Metamorphosis" title="Metamorphosis">Metamorphosis</a></li> <li><a href="/wiki/Morphology_(biology)" title="Morphology (biology)">Morphology</a></li> <li><a href="/wiki/Physiology" title="Physiology">Physiology</a></li> <li><a href="/wiki/Ecological_evolutionary_developmental_biology" title="Ecological evolutionary developmental biology">Eco-evo-devo</a> (ecological evolutionary developmental biology)</li> <li><a href="/wiki/Darwinism" title="Darwinism">Darwinism</a></li> <li><a href="/wiki/Fertilisation" title="Fertilisation">Fertilization</a></li> <li><a href="/wiki/Cleavage_(embryo)" title="Cleavage (embryo)">Cleavage</a></li> <li><a href="/wiki/Blastulation" title="Blastulation">Blastulation</a></li> <li><a href="/wiki/Gastrulation" title="Gastrulation">Gastrulation</a></li> <li><a href="/wiki/Germ_layer" title="Germ layer">Germ layers</a></li> <li><a href="/wiki/Neurulation" title="Neurulation">Neurulation</a></li> <li><a href="/wiki/Spinal_cord" title="Spinal cord">Spinal cord</a></li> <li><a href="/wiki/Metamorphosis" title="Metamorphosis">Metamorphosis</a></li> <li><a href="/wiki/Larva" title="Larva">Larva</a></li> <li><a href="/wiki/Adult" title="Adult">Adulthood</a></li> <li><a href="/wiki/Senescence" title="Senescence">Senescence</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="Notes_and_references">Notes and references</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Ontogeny&action=edit&section=18" title="Edit section: Notes and references"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFTomasello2018" class="citation journal cs1"><a href="/wiki/Michael_Tomasello" title="Michael 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"The Normative Turn in Early Moral Development". <i>Human Development</i>. <b>61</b> (4–5): 248–263. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1159%2F000492802">10.1159/000492802</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:149612818">149612818</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Human+Development&rft.atitle=The+Normative+Turn+in+Early+Moral+Development&rft.volume=61&rft.issue=4%E2%80%935&rft.pages=248-263&rft.date=2018-09-27&rft_id=info%3Adoi%2F10.1159%2F000492802&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A149612818%23id-name%3DS2CID&rft.aulast=Tomasello&rft.aufirst=Michael&rfr_id=info%3Asid%2Fen.wikipedia.org%3AOntogeny" class="Z3988"></span></span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.britannica.com/science/ontogeny-biology">"ontogeny | biology | Britannica"</a>. <i>www.britannica.com</i><span class="reference-accessdate">. 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src="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/16px-Wiktionary-logo-en-v2.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/24px-Wiktionary-logo-en-v2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/32px-Wiktionary-logo-en-v2.svg.png 2x" data-file-width="512" data-file-height="512" /></a></span> The dictionary definition of <a href="https://en.wiktionary.org/wiki/Special:Search/ontogeny" class="extiw" title="wiktionary:Special:Search/ontogeny"><i>ontogeny</i></a> at Wiktionary</li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output 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class="mw-redirect" title="Embryogenesis">Embryogenesis</a> <ul><li><a href="/wiki/Human_embryogenesis" class="mw-redirect" title="Human embryogenesis">Human</a></li> <li><a href="/wiki/Drosophila_embryogenesis" title="Drosophila embryogenesis"><i>Drosophila</i></a></li> <li><a href="/wiki/Fish_development" title="Fish development">Fish</a></li> <li><a href="/wiki/Polarity_in_embryogenesis" title="Polarity in embryogenesis">polarity</a></li></ul></li> <li><a href="/wiki/Embryology" title="Embryology">Embryology</a></li> <li><a href="/wiki/Metamerism_(biology)" title="Metamerism (biology)">Metamerism</a></li> <li><a href="/wiki/Larva" title="Larva">Larva</a></li> <li><a href="/wiki/Pupa" title="Pupa">Pupa</a></li> <li><a href="/wiki/Metamorphosis" title="Metamorphosis">Metamorphosis</a> <ul><li>Indirect development: <a href="/wiki/Holometabolism" title="Holometabolism">holometabolism</a> (<a href="/wiki/Hypermetamorphosis" title="Hypermetamorphosis">Hypermetamorphosis</a>), <a href="/wiki/Hemimetabolism" title="Hemimetabolism">hemimetabolism</a></li> <li><a href="/wiki/Direct_development" title="Direct development">Direct development</a>: <a href="/wiki/Ametabolism" title="Ametabolism">ametabolism</a></li></ul></li> <li><a href="/wiki/Model_organism" title="Model organism">Model organisms</a></li> <li><a class="mw-selflink selflink">Ontogeny</a></li> <li><a href="/wiki/Puberty" title="Puberty">Puberty</a></li> <li><a href="/wiki/Regeneration_(biology)" title="Regeneration (biology)">Regeneration</a> <ul><li><a href="/wiki/Regeneration_in_humans" title="Regeneration in humans">Human</a></li></ul></li> <li><a href="/wiki/Teratology" title="Teratology">Teratology</a></li></ul> </div></td></tr><tr><td colspan="2" class="navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Evolutionary_developmental_biology" title="Evolutionary developmental biology">Evolutionary developmental biology</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="The_development_of_phenotype" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Genarch" title="Template:Genarch"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Genarch" title="Template talk:Genarch"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Genarch" title="Special:EditPage/Template:Genarch"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="The_development_of_phenotype" style="font-size:114%;margin:0 4em">The <a href="/wiki/Morphogenesis" title="Morphogenesis">development</a> of <a href="/wiki/Phenotype" title="Phenotype">phenotype</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Key concepts</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Genotype%E2%80%93phenotype_distinction" title="Genotype–phenotype distinction">Genotype–phenotype distinction</a></li> <li><a href="/wiki/Reaction_norm" title="Reaction norm">Reaction norm</a></li> <li><a href="/wiki/Gene%E2%80%93environment_interaction" title="Gene–environment interaction">Gene–environment interaction</a></li> <li><a href="/wiki/Gene%E2%80%93environment_correlation" title="Gene–environment correlation">Gene–environment correlation</a></li> <li><a href="/wiki/Operon" title="Operon">Operon</a></li> <li><a href="/wiki/Heritability" title="Heritability">Heritability</a></li> <li><a href="/wiki/Quantitative_genetics" title="Quantitative genetics">Quantitative genetics</a></li> <li><a href="/wiki/Heterochrony" title="Heterochrony">Heterochrony</a> <ul><li><a href="/wiki/Neoteny" title="Neoteny">Neoteny</a></li></ul></li> <li><a href="/wiki/Heterotopy" title="Heterotopy">Heterotopy</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Genetic_architecture" title="Genetic architecture">Genetic architecture</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Canalisation_(genetics)" title="Canalisation (genetics)">Canalisation</a></li> <li><a href="/wiki/Genetic_assimilation" title="Genetic assimilation">Genetic assimilation</a></li> <li><a href="/wiki/Dominance_(genetics)" title="Dominance (genetics)">Dominance</a></li> <li><a href="/wiki/Epistasis" title="Epistasis">Epistasis</a></li> <li><a href="/wiki/Fitness_landscape" title="Fitness landscape">Fitness landscape</a>/<a href="/wiki/Evolutionary_landscape" title="Evolutionary landscape">evolutionary landscape</a></li> <li><a href="/wiki/Pleiotropy" title="Pleiotropy">Pleiotropy</a></li> <li><a href="/wiki/Phenotypic_plasticity" title="Phenotypic plasticity">Plasticity</a></li> <li><a href="/wiki/Polygenic_inheritance" class="mw-redirect" title="Polygenic inheritance">Polygenic inheritance</a></li> <li><a href="/wiki/Transgressive_segregation" title="Transgressive segregation">Transgressive segregation</a></li> <li><a href="/wiki/Sequence_space_(evolution)" title="Sequence space (evolution)">Sequence space</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Non-genetic influences</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Epigenetics" title="Epigenetics">Epigenetics</a></li> <li><a href="/wiki/Maternal_effect" title="Maternal effect">Maternal effect</a></li> <li><a href="/wiki/Genomic_imprinting" title="Genomic imprinting">Genomic imprinting</a></li> <li><a href="/wiki/Dual_inheritance_theory" title="Dual inheritance theory">Dual inheritance theory</a></li> <li><a href="/wiki/Polyphenism" title="Polyphenism">Polyphenism</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Developmental architecture</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Developmental_biology" title="Developmental biology">Developmental biology</a></li> <li><a href="/wiki/Morphogenesis" title="Morphogenesis">Morphogenesis</a> <ul><li><a href="/wiki/Eyespot_(mimicry)" title="Eyespot (mimicry)">Eyespot</a></li> <li><a href="/wiki/Pattern_formation" title="Pattern formation">Pattern formation</a></li></ul></li> <li><a href="/wiki/Segmentation_(biology)" title="Segmentation (biology)">Segmentation</a></li> <li><a href="/wiki/Metamerism_(biology)" title="Metamerism (biology)">Metamerism</a></li> <li><a href="/wiki/Modularity_(biology)" title="Modularity (biology)">Modularity</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Evolution of genetic systems</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Evolvability" title="Evolvability">Evolvability</a></li> <li><a href="/wiki/Robustness_(evolution)" title="Robustness (evolution)">Robustness</a></li> <li><a href="/wiki/Neutral_network_(evolution)" title="Neutral network (evolution)">Neutral networks</a></li> <li><a href="/wiki/Evolution_of_sexual_reproduction" title="Evolution of sexual reproduction">Evolution of sexual reproduction</a></li> <li><a href="/wiki/Evolutionary_tinkering" title="Evolutionary tinkering">Tinkering</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Control of development</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Systems</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Regulation_of_gene_expression" title="Regulation of gene expression">Regulation of gene expression</a></li> <li><a href="/wiki/Gene_regulatory_network" title="Gene regulatory network">Gene regulatory network</a></li> <li><a href="/wiki/Evo-devo_gene_toolkit" title="Evo-devo gene toolkit">Evo-devo gene toolkit</a></li> <li><a href="/wiki/Evolutionary_developmental_biology" title="Evolutionary developmental biology">Evolutionary developmental biology</a></li> <li><a href="/wiki/Homeobox" title="Homeobox">Homeobox</a></li> <li><a href="/wiki/Hedgehog_signaling_pathway" title="Hedgehog signaling pathway">Hedgehog signaling pathway</a></li> <li><a href="/wiki/Notch_signaling_pathway" title="Notch signaling pathway">Notch signaling pathway</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Elements</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Homeotic_gene" title="Homeotic gene">Homeotic gene</a></li> <li><a href="/wiki/Hox_gene" title="Hox gene">Hox gene</a></li> <li><a href="/wiki/Pax_genes" title="Pax genes">Pax genes</a> <ul><li><a href="/wiki/PAX6" title="PAX6">eyeless gene</a></li></ul></li> <li><a href="/wiki/DLX_gene_family" title="DLX gene family">Distal-less</a></li> <li><a href="/wiki/Engrailed_(gene)" title="Engrailed (gene)">Engrailed</a></li> <li><a href="/wiki/Cis-regulatory_element" title="Cis-regulatory element">cis-regulatory element</a></li> <li><a href="/wiki/Ligand_(biochemistry)" title="Ligand (biochemistry)">Ligand</a></li> <li><a href="/wiki/Morphogen" title="Morphogen">Morphogen</a></li> <li><a href="/wiki/Receptor_(biochemistry)" title="Receptor (biochemistry)">Cell surface receptor</a></li> <li><a href="/wiki/Transcription_factor" title="Transcription factor">Transcription factor</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Influential figures</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/C._H._Waddington" title="C. H. Waddington">C. H. Waddington</a></li> <li><a href="/wiki/Richard_Lewontin" title="Richard Lewontin">Richard Lewontin</a></li> <li><a href="/wiki/Fran%C3%A7ois_Jacob" title="François Jacob">François Jacob</a> + <a href="/wiki/Jacques_Monod" title="Jacques Monod">Jacques Monod</a> <ul><li><a href="/wiki/Lac_operon" title="Lac operon">Lac operon</a></li></ul></li> <li><a href="/wiki/Eric_F._Wieschaus" title="Eric F. Wieschaus">Eric F. Wieschaus</a></li> <li><a href="/wiki/Christiane_N%C3%BCsslein-Volhard" title="Christiane Nüsslein-Volhard">Christiane Nüsslein-Volhard</a></li> <li><a href="/wiki/William_McGinnis" title="William McGinnis">William McGinnis</a></li> <li><a href="/wiki/Michael_Levine_(biologist)" title="Michael Levine (biologist)">Mike Levine</a></li> <li><a href="/wiki/Sean_B._Carroll" title="Sean B. Carroll">Sean B. Carroll</a> <ul><li><i><a href="/wiki/Endless_Forms_Most_Beautiful_(book)" title="Endless Forms Most Beautiful (book)">Endless Forms Most Beautiful</a></i></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Debates</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Nature_versus_nurture" title="Nature versus nurture">Nature versus nurture</a></li> <li><a href="/wiki/Morphogenetic_field" title="Morphogenetic field">Morphogenetic field</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div><a href="/wiki/Index_of_evolutionary_biology_articles" title="Index of evolutionary biology articles">Index of evolutionary biology articles</a></div></td></tr></tbody></table></div> <style data-mw-deduplicate="TemplateStyles:r1130092004">.mw-parser-output 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