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Neurogenic placode
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<h2 id="in-humans">In humans</h2> <p>The cranial placodes that have neurogenic potential (i.e. give rise to <a href="/facts/Neuron/G7CyTVdH">neurons</a>) can be divided into two groups, the dorsolateral placodes and the epibranchial placodes.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p> <ul><li>dorsolateral placodes includes: <ul><li>The trigeminal placode,<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> which consists of ophthalmic and maxillomandibular parts, and gives rise to the cells of the <a href="/facts/Trigeminal_ganglion/zJcSUs5s">trigeminal ganglion</a></li> <li>The <a href="/facts/Otic_placode/n6XEzupV">otic placode</a> forms the <a href="/facts/Otic_pit/7AbQh0Tx">otic pit</a> and the <a href="/facts/Otic_vesicle/R8I42FUk">otic vesicle</a>, giving rise eventually to organs of hearing and equilibrium.</li></ul></li> <li>The epibranchial or <i>epipharyngeal</i> placodes generate the distal portion of the ganglia of cranial nerves VII, IX and X:<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> <ul><li>The geniculate placode, associated with the first <a href="/facts/Pharyngeal_groove/mQt5YA0Y">pharyngeal groove</a>, generates the <a href="/facts/Geniculate_ganglion/WBLVIe3N">geniculate ganglion</a> and distal parts of <a href="/facts/Cranial_nerve_VII/xJq3Vvch">cranial nerve VII</a></li> <li>The petrosal placode, associated with the second pharyngeal groove, generates the <a href="/facts/Inferior_ganglion_of_glossopharyngeal_nerve/1sMwxI7A">inferior ganglion of glossopharyngeal nerve</a> and distal parts of <a href="/facts/Cranial_nerve_IX/XBAjNStT">cranial nerve IX</a></li> <li>The nodosal placode, associated with the third <a href="/facts/Branchial_cleft/mQt5YA0Y">branchial cleft</a>, generates the <a href="/facts/Nodose_ganglion/YEDhdVY2">nodose ganglion</a> and distal parts of <a href="/facts/Cranial_nerve_X/cKQR0rLm">cranial nerve X</a></li></ul></li> <li>The <a href="/facts/Nasal_placode/MplhU5bd">olfactory placode</a> (or <i>nasal placode)</i><a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> gives rise to the <a href="/facts/Olfactory_epithelium/EycjMyFv">olfactory epithelium</a> of the <a href="/facts/Human_nose/fmhw8BmP">nose</a>.</li> <li>The cranial placodes that do not give rise to neurons are: <ul><li>The <a href="/facts/Lens_placode/DNwQGM1S">lens placode</a> under the direction of the <a href="/facts/Optic_vesicle/96Ljs5K6">optic vesicle</a> gives rise to the <a href="/facts/Lens_of_the_eye/yWz7AdHV">lens of the eye</a>.</li> <li>The <a href="/facts/Adenohypophyseal_placode/gdrQyldF">adenohypophyseal placode</a>, which forms the <a href="/facts/Anterior_lobe_of_the_pituitary_gland/uUj4jzRq">anterior lobe of the pituitary gland</a>.</li></ul></li></ul> <h2 id="other-animals">Other animals</h2> <ul><li>The profundal placode, corresponding to the ophthalmic lobe of the trigeminal complex. In <a href="/facts/Xenopus/AfAtcsyA">Xenopus</a>, this remains partly unfused.</li> <li>In fish and larval amphibians, the lateral line placodes, which give rise to the <a href="/facts/Lateral_line_system/u88dwyxh">lateral line system</a>.</li> <li>The hypobranchial placodes, a neurogenic placode found in some <a href="/facts/Amphibian/r2BleD2W">amphibians</a> of unknown function<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a></li></ul> <h2 id="other-ectodermal-placodes">Other ectodermal placodes</h2> <p>The term <i>placode</i> or <i>ectodermal placode</i> is sometimes used to refer specifically to cranial or neurogenic placodes, but is also used for areas of the <a href="/facts/Ectoderm/lg5p0jTL">ectoderm</a> that give rise to structures such as <a href="/facts/Mammary_glands/6fVBnNSA">mammary glands</a>, <a href="/facts/Feather/sxbf96nF">feathers</a> and <a href="/facts/Hair/L7vt9FL3">hair</a>. </p> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Park, Saint-Jeannet (2010). "Introduction". Induction and Segregation of the Vertebrate Cranial Placodes. Morgan & Claypool Life Sciences. <a href="https://www.ncbi.nlm.nih.gov/books/NBK53171/" target="_blank">https://www.ncbi.nlm.nih.gov/books/NBK53171/</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Park, Saint-Jeannet (2010). "Introduction". Induction and Segregation of the Vertebrate Cranial Placodes. Morgan & Claypool Life Sciences. <a href="https://www.ncbi.nlm.nih.gov/books/NBK53171/" target="_blank">https://www.ncbi.nlm.nih.gov/books/NBK53171/</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Streit, A (2007). "The preplacodal region: an ectodermal domain with multipotential progenitors that contribute to sense organs and cranial sensory ganglia". The International Journal of Developmental Biology. 51 (6–7): 447–61. doi:10.1387/ijdb.072327as. PMID 17891708. <a href="https://kclpure.kcl.ac.uk/portal/en/publications/e52a117f-5222-4ea5-83f4-4e8cc4111ef4" target="_blank">https://kclpure.kcl.ac.uk/portal/en/publications/e52a117f-5222-4ea5-83f4-4e8cc4111ef4</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Park, Saint-Jeannet (2010). "Introduction". Induction and Segregation of the Vertebrate Cranial Placodes. Morgan & Claypool Life Sciences. <a href="https://www.ncbi.nlm.nih.gov/books/NBK53171/" target="_blank">https://www.ncbi.nlm.nih.gov/books/NBK53171/</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Sommer, L. (2013-01-01), Rubenstein, John L. R.; Rakic, Pasko (eds.), "Chapter 20 - Specification of Neural Crest- and Placode-Derived Neurons", Patterning and Cell Type Specification in the Developing CNS and PNS, Oxford: Academic Press, pp. 385–400, doi:10.1016/b978-0-12-397265-1.00100-3, ISBN 978-0-12-397265-1, retrieved 2020-10-26 <a href="978-0-12-397265-1" target="_blank">978-0-12-397265-1</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Sommer, L. (2013-01-01), Rubenstein, John L. R.; Rakic, Pasko (eds.), "Chapter 20 - Specification of Neural Crest- and Placode-Derived Neurons", Patterning and Cell Type Specification in the Developing CNS and PNS, Oxford: Academic Press, pp. 385–400, doi:10.1016/b978-0-12-397265-1.00100-3, ISBN 978-0-12-397265-1, retrieved 2020-10-26 <a href="978-0-12-397265-1" target="_blank">978-0-12-397265-1</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>hednk-027—Embryo Images at University of North Carolina <a href="https://syllabus.med.unc.edu/courseware/embryo_images/unit-hednk/hednk_htms/hednk027.htm" target="_blank">https://syllabus.med.unc.edu/courseware/embryo_images/unit-hednk/hednk_htms/hednk027.htm</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Park, Saint-Jeannet (2010). "Introduction". Induction and Segregation of the Vertebrate Cranial Placodes. Morgan & Claypool Life Sciences. <a href="https://www.ncbi.nlm.nih.gov/books/NBK53171/" target="_blank">https://www.ncbi.nlm.nih.gov/books/NBK53171/</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> </ol>