Editing XY sex-determination system (section)

=== 20th century genetics ===
[[File:Nettie Maria Stevens.jpg|thumb|[[Nettie Stevens]] in 1904]]
[[File:Edmund Beecher Wilson between about 1885 and 1891.jpg|thumb|[[Edmund Beecher Wilson]], before 1891]]
[[Nettie Stevens]] (working with beetles) and [[Edmund Beecher Wilson]] (working with [[hemiptera]]) are credited with independently discovering, in 1905, the chromosomal XY sex-determination system in insects: the fact that males have XY sex [[chromosomes]] and females have XX sex chromosomes.<ref name="Brush-1978">{{cite journal | vauthors = Brush SG | title = Nettie M. Stevens and the discovery of sex determination by chromosomes | journal = Isis; an International Review Devoted to the History of Science and Its Cultural Influences | volume = 69 | issue = 247 | pages = 163–172 | date = June 1978 | pmid = 389882 | doi = 10.1086/352001 | s2cid = 1919033 | jstor = 230427 }}</ref><ref name="Stevens">{{Cite web|url=http://www.dnaftb.org/9/bio.html|title=Specialized chromosomes determine sex. - Nettie Maria Stevens | work = DNA from the Beginning |access-date=2016-07-07|url-status=live|archive-url=https://web.archive.org/web/20121001065058/http://www.dnaftb.org/9/bio.html|archive-date=2012-10-01 | publisher = DNA Learning Center, Cold Spring Harbor Laboratory | location = Laurel Hollow, New York }}</ref><ref>{{cite book | veditors = Heilbron JL | title = The Oxford Companion to the History of Modern Science | publisher = Oxford University Press | date = 2003 | chapter = Genetics | isbn = 978-0-19-511229-0 }}</ref> In the early 1920s, [[Theophilus Painter]] demonstrated that sex in humans (and other mammals) was also determined by the X and Y chromosomes, and the chromosomes that make this determination are carried by the spermatozoa.<ref>{{cite book | vauthors = Glass B | date = 1990 | chapter-url = https://www.nasonline.org/wp-content/uploads/2024/06/painter-theophilus-shickel.pdf | chapter = Theophilus Shickel Painter 1889—1969 | title = Biographical Memoirs | volume = 59 | publisher = National Academy of Sciences | location = Washington DC | isbn = 978-0-309-04198-0 }}</ref>

The first clues to the existence of a factor that determines the development of testis in mammals came from experiments carried out by [[Alfred Jost]],<ref>{{cite journal | vauthors = Jost A | title = Recherches sur la differenciation sexuelle de l'embryon de lapin | trans-title = Research on sexual differentiation of the rabbit embryo | journal = Archives d'anatomie microscopique et de morphologie expérimentale | trans-journal = Archives of microscopic anatomy and experimental morphology | language = fr | volume = 36 | pages = 271–315 | date = 1947 }}</ref> who castrated embryonic rabbits in utero and noticed that they all acquired a female [[phenotype]].<ref name="Zhao-2019">{{cite journal | vauthors = Zhao F, Yao HH | title = A tale of two tracts: history, current advances, and future directions of research on sexual differentiation of reproductive tracts† | journal = Biology of Reproduction | volume = 101 | issue = 3 | pages = 602–616 | date = September 2019 | pmid = 31058957 | pmc = 6791057 | doi = 10.1093/biolre/ioz079 }}</ref>

In 1959, [[C. E. Ford]] and his team, in the wake of Jost's experiments, discovered<ref>{{cite journal | vauthors = Ford CE, Jones KW, Polani PE, De Almeida JC, Briggs JH | title = A sex-chromosome anomaly in a case of gonadal dysgenesis (Turner's syndrome) | journal = Lancet | volume = 1 | issue = 7075 | pages = 711–713 | date = April 1959 | pmid = 13642858 | doi = 10.1016/S0140-6736(59)91893-8 }}</ref> that the Y chromosome was needed for a fetus to develop as male when they examined patients with [[Turner syndrome|Turner's syndrome]], who grew up as phenotypic females, and found them to be X0 ([[hemizygous]] for X and no Y). At the same time, Jacob & Strong described a case of a patient with [[Klinefelter syndrome]] (XXY),<ref>{{cite journal | vauthors = Jacobs PA, Strong JA | title = A case of human intersexuality having a possible XXY sex-determining mechanism | journal = Nature | volume = 183 | issue = 4657 | pages = 302–303 | date = January 1959 | pmid = 13632697 | doi = 10.1038/183302a0 | s2cid = 38349997 | bibcode = 1959Natur.183..302J }}</ref> which implicated the presence of a Y chromosome in development of maleness.<ref name="Schoenwolf-2009" />

All these observations led to a consensus that a dominant gene that determines testis development ([[Testis determining factor|TDF]]) must exist on the human Y chromosome.<ref name="Schoenwolf-2009" />  The search for this [[Testis determining factor|testis-determining factor]] (TDF) led to [[Peter Goodfellow (geneticist)|Peter Goodfellow's]] team of scientists<ref>{{cite journal | vauthors = Sinclair AH, Berta P, Palmer MS, Hawkins JR, Griffiths BL, Smith MJ, Foster JW, Frischauf AM, Lovell-Badge R, Goodfellow PN | title = A gene from the human sex-determining region encodes a protein with homology to a conserved DNA-binding motif | journal = Nature | volume = 346 | issue = 6281 | pages = 240–244 | date = July 1990 | pmid = 1695712 | doi = 10.1038/346240a0 | s2cid = 4364032 | bibcode = 1990Natur.346..240S }}</ref> in 1990 to discover a region of the Y chromosome that is necessary for the male sex determination, which was named [[SRY]] (sex-determining region of the Y chromosome).<ref name="Schoenwolf-2009">{{cite book| vauthors = Schoenwolf GC |title=Larsen's human embryology|date=2009|publisher=Churchill Livingstone/Elsevier|location=Philadelphia|isbn=978-0-443-06811-9 |chapter=Development of the Urogenital system|edition=4th |pages=307–9}}</ref>