Autoradiographic localization of estrogen-concentrating cells in the brain and pituitary of the oyster toadfish

We examined the distribution of [3H] estradiol-concentrating neurons in gonadectomized male and female oyster toadfish (Opsanus tau) by thaw-mount autoradiography. Compared to other teleosts studied in this fashion, the toadfish is of interest because of its reliance on male sound production during courtship. Labeled cells were found in the pars distalis of the pituitary and in periventricular midline regions of the forebrain. These included the ventral, supracommissural and posterior nuclei of the ventral telencephalon, nucleus preopticus parvocellularis anterior, the ventral, lateral, dorsal and caudal hypothalamus, and the periventricular nucleus of the posterior tuberculum of the thalamus. For the first time in a teleost, estrogen-concentrating cells were recorded in the brainstem, in sites including the optic tectum and torus semicircularis. In contrast to a previous study with testosterone, two prominent nuclei in the medulla were negative. With some additions, the distribution of estrogen-concentrating neurons conformed to the general pattern in other teleosts.