Localization of steroid-concentrating cells in the central nervous system of the frog Rana esculenta

Steroid-concentrating cells were localized using steroid hormone autoradiography in the brain of Rana esculenta after systemic administration of tritiated estradiol and testosterone. Highest numbers of labeled cells were found in the anterior preoptic area, in the ventral infundibular nucleus, and in the pituitary. Other sites of tritiated sex steroid uptake were in the striatum, septum, amygdala, thalamus, tectum, torus semicircularis, and dorsal tegmental area of the medulla. No differences were seen between males and females. These results complement the ones obtained in Rana pipiens and confirm that in the genus Rana the distribution of testosterone- and estradiol-concentrating neurons is invariant in many respects.