Locations of androgen-concentrating cells in the brain of Xenopus laevis: autoradiography with 3H-dihydrotestosterone.

The distribution of hormone-concentrating cells in the brains of South African clawed frogs, Xenopus laevis, was examined autoradiographically after the administration of 3H-dihydrotestosterone. Hormone-accumulating cells were found in cranial nerve nucleus IX-X and adjacent smaller cells, a presumed medullary vestibular nucleus, a presumed sensory nucleus of cranial nerve V, dorsal tegmental area of the medulla, laminar nucleus of the torus semicircularis, ventral thalamus, and anterior pituitary. The pattern of dihydrotestosterone-labelled cells differs from previously reported results following testosterone or estradiol administration. Unlike these latter hormones, dihydrotestosterone does not accumulate in anterior preoptic or ventral infundibular nuclei. Both androgens but not estradiol label medullary motor neurons; limbic telencephalic nuclei appear to concentrate only estradiol. Hormone-concentrating brain nuclei in X. laevis have been implicated in neuro-endocrine regulation and the control of male and female reproductive behaviors.