Immunocytochemical distribution of androgen receptors in the hypothalamus and pituitary of the fetal baboon in late gestation.

Parturition in primates is hypothesized to be precipitated by aromatization of fetal adrenal androgens to estrogens in the placenta. We immunocytochemically localized androgen receptor (AR) in the hypothalamus and pituitary of late gestation fetal baboons. AR immunostaining was: strongest in lateral hypothalamic, arcuate, lateral mammillary, supra-mammillary and paraventricular (small neuronal subset) nuclei; of varying intensity in ventromedial, medial preoptic and anterior hypothalamic nuclei and bed nucleus of the stria terminalis; weakest in supraoptic and suprachiasmatic nuclei; and not found in pituitary. We conclude that AR are potentially in position in the fetal hypothalamus to participate in regulation of fetal adrenal androgen production during late gestation.