Editing Androgen insensitivity syndrome (section)

===Androgens in fetal development===
[[Human embryos]] develop similarly for the first six weeks, regardless of genetic sex (46,XX or 46,XY karyotype); the only way to tell the difference between 46,XX or 46,XY embryos during this time period is to look for [[Barr bodies]] or a Y chromosome.<ref name="2006 jones" />  The gonads begin as bulges of tissue called the [[gonadal ridge|genital ridges]] at the back of the [[abdominal cavity]], near the midline.  By the fifth week, the genital ridges [[sexual differentiation|differentiate]] into an outer [[Cortex (anatomy)|cortex]] and an inner [[wikt:medulla|medulla]], and are called [[Development of the gonads|indifferent gonads]].<ref name="2006 jones" />  By the sixth week, the indifferent gonads begin to differentiate according to genetic sex.  If the karyotype is 46,XY, testes develop due to the influence of the [[Y chromosome]]'s ''SRY'' gene.<ref name="2006 achermann" /><ref name="1995 simpson" />  This process does not require the presence of androgen, nor a functional androgen receptor.<ref name="2006 achermann" /><ref name="1995 simpson" />

Until around the seventh week of development, the embryo has indifferent [[Sex determination and differentiation (human)|sex accessory ducts]], which consist of two pairs of ducts: the [[Müllerian ducts]] and the [[Wolffian ducts]].<ref name="2006 jones" />  [[Sertoli cells]] within the testes secrete [[anti-Müllerian hormone]] around this time to suppress the development of the Müllerian ducts, and cause their degeneration.<ref name="2006 jones" />  Without this anti-Müllerian hormone, the Müllerian ducts develop into the [[Female reproductive system#Internal genitalia|female internal genitalia]] ([[uterus]], [[cervix]], [[fallopian tubes]], and [[Vagina#Gross anatomy|upper vaginal barrel]]).<ref name="2006 jones" />  Unlike the Müllerian ducts, the Wolffian ducts will not continue to develop by default.<ref name="2003 yong 9" />  In the presence of testosterone and functional androgen receptors, the Wolffian ducts develop into the [[epididymis|epididymides]], [[vas deferens|vasa deferentia]], and [[seminal vesicles]].<ref name="2006 jones" />  If the testes fail to secrete testosterone, or the androgen receptors do not function properly, the Wolffian ducts degenerate.<ref name="2004 hannema 89" />

[[File:Androgen dependencies of male genital tissues.png|thumb|Masculinization of the male genitalia is dependent on both testosterone and dihydrotestosterone.<ref name="2000 gilbert" />]]
Masculinization of the [[male external genitalia]] (the [[Human penis|penis]], penile [[urethra]], and [[scrotum]]), as well as the [[prostate]], are dependent on the androgen [[dihydrotestosterone]].<ref name="2008 oakes 21" /><ref name="1999 roy 55" /><ref name="1999 kokontis 55" /><ref name="2009 rajender 91" />  Testosterone is converted into dihydrotestosterone by the 5-alpha reductase enzyme.<ref name="2006 sobel 91" />  If this enzyme is absent or deficient, then dihydrotestosterone is not created, and the external male genitalia do not develop properly.<ref name="2008 oakes 21" /><ref name="1999 roy 55" /><ref name="1999 kokontis 55" /><ref name="2009 rajender 91" /><ref name="2006 sobel 91" />  As is the case with the [[Male reproductive system#Internal genitalia|internal male genitalia]], a functional androgen receptor is needed for dihydrotestosterone to regulate the [[gene transcription|transcription of target genes]] involved in development.<ref name="1998 wang 83" />