Gonadal hormones and brain development: Cellular aspects of sexual differentiation

Abstract

Sexual differentiation of the neural control of reproductive function with respect to both gonadotropin secretion and sexual behavior is thought to result from exposure of the brain to testicular androgens during a very restricted or critical period of CNS differentiation and development, when the tissue is competent to respond to the hormone, and after which it is refractory or responds in a reversible manner. This paper reviews the cellular aspects of sexual differentiation with particular emphasis on the morphological expression of the gonadal hormonal effects in the adult brain. It presents experimental evidence for the morphogenetic basis for the observed steroid effects by showing how the addition of steroid to undifferentiated hypothalamic cultures produces a selective neuritic response that is steroid-dependent. These results suggest that since afferent axonal input and temporal factors are critical for dendritic and synaptic differentiation, steroid-induced variations in neuritic development could result in gender-specific responses seen in sexual differentiation of reproductive function. © 1978 by the American Society of Zoologists.