Editing Sexual differentiation (section)

{{Short description|Embryonic development of sex differences}}
{{Infobox anatomy
|Name=Sexual differentiation
|Image= 2915_Sexual_Differentation-02.jpg
|Caption= Differentiation of the male and female reproductive systems does not occur until the fetal period of development.
|Width = 300
}}
'''Sexual differentiation''' is the process of development of the [[sex]] differences between [[male]]s and [[female]]s from an undifferentiated [[zygote]].<ref name="Beukeboom">{{Cite book|last1=Beukeboom|first1=Leo W.|last2=Perrin|first2=Nicolas|title=The Evolution of Sex Determination|date=2014|publisher=Oxford University Press|isbn=978-0199657148|page=158|url=https://books.google.com/books?id=7yrnAwAAQBAJ&pg=PA158}}</ref><ref name="Koob">{{Cite book|last1=Koob|first1=George F.|title=Encyclopedia of Behavioral Neuroscience|date=2010|publisher=Elsevier|isbn=978-0080914558|page=21|url=https://books.google.com/books?id=DfV-BwAAQBAJ&pg=RA1-PA21}}</ref> Sex differentiation is usually distinct from [[Sex-determination system|sex determination]]; sex determination is the designation of the development stage towards either male or female, while sex differentiation is the pathway towards the development of the [[phenotype]].<ref>{{Cite book|url=https://books.google.com/books?id=7yrnAwAAQBAJ&q=the+evolution+of+sex+determination|title=The Evolution of Sex Determination|vauthors=Beukeboom LW, Perrin N|date=2014|publisher=Oxford University Press|isbn=978-0-19-965714-8|pages=16|language=en}}</ref>

In many species, testicular or ovarian differentiation begins with the appearance of [[Sertoli cell]]s in males and [[granulosa cell]]s in females.<ref name=":62">{{Cite book|last=Pandian|first=T. J.|title=Endocrine Sex Differentiation in Fish|date=2013-05-07|publisher=CRC Press|doi=10.1201/b14771|isbn=978-0-429-10222-6}}</ref><ref>{{Cite journal |last=Bouma |first=Gerrit J. |last2=Hudson |first2=Quanah J. |last3=Washburn |first3=Linda L. |last4=Eicher |first4=Eva M. |date=February 2010 |title=New candidate genes identified for controlling mouse gonadal sex determination and the early stages of granulosa and Sertoli cell differentiation |url=https://pubmed.ncbi.nlm.nih.gov/19864314 |journal=Biology of Reproduction |volume=82 |issue=2 |pages=380–389 |doi=10.1095/biolreprod.109.079822 |issn=1529-7268 |pmc=2809227 |pmid=19864314}}</ref>

As [[Embryo|embryos]] develop into mature adults, sex differences develop at many levels, including [[chromosome]]s, [[gonad]]s, [[hormone]]s, and [[anatomy]]. Beginning with determining sex by genetic and/or environmental factors, humans and other organisms proceed towards different differentiation pathways as they grow and develop.