Males lacking this hormone are infertile because the testes do not descend. In females, lack of this hormone deregulates the menstrual cycle. AMH may have other roles in sex determination besides causing the breakdown of the M llerian ducts. It may cause sex reversal in some mammals, and may become useful as an anti-tumor drug. The mechanisms of breast development.
Breast tissue has a sexually dimorphic mode of development.
Testosterone inhibits breast development, while estrogen promotes it. Most breast development is accomplished after birth, and different hormones act during puberty and pregnancy to cause breast enlargement and differentiation. Diethylstilbesterol was a drug given to women to ease their pregnancies. Unfortunately, it was later found to alter the reproductive tract of female fetuses. The mechanism of DES action is thought to involve the repression of the Hox genes that instruct the regional specificity of the M llerian duct.