Editing Testosterone (section)

==Other species==
Testosterone is observed in most vertebrates. Testosterone and the classical nuclear [[androgen receptor]] first appeared in [[gnathostome]]s (jawed vertebrates).<ref name="pmid19456336">{{cite journal | vauthors = Guerriero G | title = Vertebrate sex steroid receptors: evolution, ligands, and neurodistribution | journal = Annals of the New York Academy of Sciences | volume = 1163 | issue = 1| pages = 154–68 | year = 2009 | pmid = 19456336 | doi = 10.1111/j.1749-6632.2009.04460.x | bibcode = 2009NYASA1163..154G | s2cid = 5790990 }}</ref> [[Agnathan]]s (jawless vertebrates) such as [[lamprey]]s do not produce testosterone but instead use [[androstenedione]] as a male sex hormone.<ref name="pmid17931674">{{cite journal | vauthors = Bryan MB, Scott AP, Li W | s2cid = 33753909 | title = Sex steroids and their receptors in lampreys | journal = Steroids | volume = 73 | issue = 1 | pages = 1–12 | year = 2008 | pmid = 17931674 | doi = 10.1016/j.steroids.2007.08.011 }}</ref> [[Fish]] make a slightly different form called [[11-ketotestosterone]].<ref name="isbn0-87893-617-3">{{cite book | vauthors = Nelson RF | title = An introduction to behavioral endocrinology | publisher = Sinauer Associates | location = Sunderland, Mass | year = 2005 | page = 143 | isbn = 978-0-87893-617-5 }}</ref> Its counterpart in insects is [[ecdysone]].<ref name="De_Loof_2006">{{cite journal | vauthors = De Loof A | title = Ecdysteroids: the overlooked sex steroids of insects? Males: the black box | journal = Insect Science |date=October 2006 | volume = 13 | issue = 5 | pages = 325–338 | doi = 10.1111/j.1744-7917.2006.00101.x | bibcode = 2006InsSc..13..325D | s2cid = 221810929 }}</ref> The presence of these ubiquitous steroids in a wide range of animals suggest that [[sex hormone]]s have an ancient evolutionary history.<ref name="Mechoulam_1984">{{cite journal | vauthors = Mechoulam R, Brueggemeier RW, Denlinger DL | s2cid = 31950471 | title = Estrogens in insects | journal = Cellular and Molecular Life Sciences |date=September 1984 | volume = 40 | issue = 9 | pages = 942–44 | doi = 10.1007/BF01946450 }}</ref>