Volumetric analysis of sexually dimorphic limbic nuclei in normal and sex-reversed whiptail lizards

Sex differences in the size of key Limbic nuclei have been found in many sp ecies. In some of these species, steroid hormones have been implicated in b oth the development and the maintenance of the sex difference. However, the possible role of sex-specific genes has not been examined, in part due to lack of an appropriate model system. In this study we measured the size of the ventromedial hypothalamus and preoptic area-anterior hypothalamus in no rmal female whiptail lizards and in genetic female whiptails that had been sex-reversed by treatment early in development with the aromatase inhibitor fadrozole. We found no difference in the size of these two nuclei between females and the sex-reversed animals. These results suggest that either the sex-reversing treatment itself interfered with the masculinization process , or that a male genome is required to produce a male-like limbic phenotype . (C) 1999 Elsevier Science B.V. All rights reserved.