Anatomical distribution of estrogen, androgen, progestin, corticosteroid and thyroid hormone target sites in the brain of mammals: Phylogeny and ontogeny

Abstract

The pattern of the anatomical distribution of estrogen target cells in insectivores, rodents and primates is similar. It shows relationship to the patterns observed in non-mammalian vertebrates. In the forebrain it includes preoptic-septal, central hypothalamic, thalamic and allocortical sites. In neonatal and fetal rodents similar target sites can be demonstrated and evolve during embryonic development; however, the nuclear groups are not as well differentiated and the appearance of steroid hormone receptors does not occur simultaneously in them. Androgen target cells are accumulated at sites that overlap in part with those of estradiol, but in addition are found extensively in areas associated with psychomotor and somatomotor functions, including floor-plate derivatives in the lower brain stem and spinal cord. Glucocorticosteroids show extensive localization in neurons of the allocortex. This indicates a phylogenetically recent forebrain acquisition, compared to the sex steroids. Thyroid hormones show nuclear concentration in many neurons, in addition to selective uptake in tanycytic ependyma, choroid plexus and certain neuropil. The close topographic relationship of hormone target cells to the recess organs of the ventricular system led us to propose the concept of interrelated periventricular secretory units. © 1978 by the American Society of Zoologists.