A Neuroendocrine Approach to Brain Function: Localization of Sex Steroid Concentrating Cells in Vertebrate Brains

Sex steroid concentrating cells in brain can be demonstrated by the specialized technique of steroid autoradiography. With this technique we have demonstrated the presence and the pattern of sex steroid concentrating cells in a representative species from every major class of vertebrate. This paper discusses the details of the pattern of binding cells found in a teleost, the paradise fish, Macropodus opercularis ; a reptile, the lizard, Anolis carolinemis ; and a carnivore, the mink, Mustela vison . The majority of sex steroid concentrating cells are found in the medial preoptic area, the medial hypothalamus, limbic structures and specific areas of the mesencephalon deep to the tectum. The regions containing the largest numbers of labelled cells have been demonstrated in each species with other techniques to be involved in neuroendocrine regulation or control of sex behavior.