{{Short description|Embryo forming part of yolk}}
[[File:Cleavage.png|thumb|Embryo of Zebrafish undergoing cleavage]] The '''blastodisc''', also called the '''germinal disc''', is the embryo-forming part on the yolk of the egg of an animal that undergoes discoidal meroblastic cleavage.<ref name="MW1">{{cite web |title=Definition of BLASTODISC |url=https://www.merriam-webster.com/dictionary/blastodisc |website=www.merriam-webster.com |access-date=15 October 2022 |language=en}}</ref> Discoidal cleavage occurs in those animals with a large proportion of yolk in their eggs, and include insects, fish, reptiles and birds.<ref name="Gilbert">{{cite book |last1=Gilbert |first1=Scott F. |title=Developmental biology |date=2006 |publisher=Sinauer Associates Publishers |location=Sunderland, Mass. |isbn=9780878932504 |page=215 |edition=8th}}</ref> The blastodisc is a small disc of cytoplasm that sits on top of the yolk. In birds, it is a small, circular, white spot (approximately 1.5-3 mm across) on the surface of the yellow yolk of an egg, at the animal pole.<ref name="Gilbert2">{{cite book |last1=Gilbert |first1=Scott F. |title=Developmental biology |date=2006 |publisher=Sinauer Associates Publishers |location=Sunderland, Mass. |isbn=9780878932504 |pages=336–337 |edition=8th}}</ref>
==References== {{Reflist}} *[https://www.ncbi.nlm.nih.gov/books/NBK10100/ Early Development in Fish] *[https://www.ncbi.nlm.nih.gov/books/NBK10070/ Early Development in Birds]
Category:Oology Category:Animal developmental biology
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