Sexual dimorphism in human and canine spinal cord: role of early androgen.
Onuf's nucleus, located in the sacral spinal cord of dogs, cats, and primates, innervates perineal muscles involved in copulatory behavior. A sexual dimorphism in Onuf's nucleus was found in humans and dogs: males have significantly more motoneurons in this nucleus than do females. Prenatal androgen treatment of female dogs eliminated the dimorphism. In the homologous nucleus in rats, a similar effect of androgen has been shown to involve sparing of motoneurons from cell death. These results establish a morphological sex difference in a human central nervous system region of known function; well-studied animal models suggest explanations of the development of this dimorphism.
Forger
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Breedlove
S M
SM
D000818:Animals; D004285:Dogs; D006801:Humans; D009046:Motor Neurons / Q000166:cytology; D012727:Sex Characteristics; D012733:Sex Differentiation; D013116:Spinal Cord / Q000033:anatomy & histology / Q000196:embryology*; D013739:Testosterone / Q000494:pharmacology*
D013739:Testosterone