Neuroanatomical studies performed on rats and on hilmans point to a sexual dymorphism in various regions of the nervous system. Differences in size of nervous structures (hypothalamic nudei, corpus callous, comissura anterior, etc) between homosexuals and heterosexnals have been reported (LeVay; Allen, Gorki, etc). Several studies showed the role of hormonal factors and its disturbances during the perinatal development on the homosexual orientation. Genetical influences have been explored by a wide range of studies, especially on twins, beginning by Kallman 's research and ending by recent findings of Hamei conceming the role of genes from the site Xq28 on the homosexual preference. Promising investigations regards the impact of stress which by demasculinizing effect could increase in animals and humans the incidence of Homosexuality (Dorner et al.). A short outlook on the attitude of psychiatric conceming homosexuality (DSM4 and ICD) point to the differences between syntonic, accepted homosexuality, and the dystonic, distressing one. The existing controversies on the importance and mechanisms of the above mentioned neurobiological dimensions-which are interrelated-on the issues of homosexual orientation and identity request more multi-and interdisciplinary studies.
KEYWORDS: sexual dymorphism, hormonal factors, homosexual behavior.