Editing Sex (section)

==== XY sex determination ====
[[File:Drosophila XY sex-determination.svg|thumb|The common fruit fly has an [[XY sex-determination system]], as do humans and most mammals.]]
Humans and most other [[mammal]]s have an [[XY sex-determination system]]: the [[Y chromosome]] carries factors responsible for triggering male development, making XY sex determination mostly based on the presence or absence of the [[Y chromosome]]. It is the male [[gamete]] that determines the sex of the offspring.<ref name="Wallis-2008">{{cite journal|vauthors=Wallis MC, Waters PD, Graves JA|date=October 2008|title=Sex determination in mammals – before and after the evolution of SRY|journal=Cellular and Molecular Life Sciences|volume=65|issue=20|pages=3182–95|doi=10.1007/s00018-008-8109-z|pmid=18581056|s2cid=31675679|pmc=11131626}}</ref> In this system XX mammals typically are female and XY typically are male.<ref name="Bachtrog-2014" /> However, individuals with [[Klinefelter syndrome|XXY]] or [[XYY syndrome|XYY]] are males, while individuals with [[Turner syndrome|X]] and [[Triple X syndrome|XXX]] are females.<ref name="Hake-2008" /> Unusually, the [[platypus]], a [[monotreme]] mammal, has ten sex chromosomes; females have ten X chromosomes, and males have five X chromosomes and five Y chromosomes. Platypus egg cells all have five X chromosomes, whereas sperm cells can either have five X chromosomes or five Y chromosomes.<ref>{{cite book | vauthors = Pierce BA |title=Genetics: a conceptual approach |date=2012 |publisher=W.H. Freeman |isbn=978-1-4292-3250-0 |edition=4th |location=New York |pages=73–74 |oclc=703739906}}</ref>

XY sex determination is found in other organisms, including insects like the [[Drosophila melanogaster|common fruit fly]],<ref name="Kaiser-2010">{{cite journal|vauthors=Kaiser VB, Bachtrog D|year=2010|title=Evolution of sex chromosomes in insects|journal=Annual Review of Genetics|volume=44|pages=91–112|doi=10.1146/annurev-genet-102209-163600|pmc=4105922|pmid=21047257}}</ref> and some plants.<ref name="Dellaporta-1993">{{cite journal | vauthors = Dellaporta SL, Calderon-Urrea A | title = Sex determination in flowering plants | journal = The Plant Cell | volume = 5 | issue = 10 | pages = 1241–1251 | date = October 1993 | pmid = 8281039 | pmc = 160357 | doi = 10.1105/tpc.5.10.1241 | jstor = 3869777 }}</ref> In some cases, it is the number of X chromosomes that determines sex rather than the presence of a Y chromosome.<ref name="Hake-2008" /> In the fruit fly individuals with XY are male and individuals with XX are female; however, individuals with XXY or XXX can also be female, and individuals with X can be males.<ref>{{cite book| vauthors = Fusco G, Minelli A |author-link2=Alessandro Minelli (biologist) |url={{GBurl|id=AKGsDwAAQBAJ}}|title=The Biology of Reproduction|year=2019|publisher=Cambridge University Press|isbn=978-1-108-49985-9|pages=306–308 }}</ref>