[Consequences of disturbed sex-hormone action in the central nervous system: behavioral, anatomical and functional changes].

Experimental studies revealed that transient action of sex steroids during perinatal period is crucial for the development of male sexual behavior and sexually dimorphic brain anatomy. Meanwhile, the lack of gonadal steroids in female foetus and estrogen effects at puberty determine female behavior together with female type of anatomical brain structures and of endocrine functions. In men psychic sex consists of gender identity (self-estimation), gender role (objective estimation of sex behavior). In addition, a sexual psycho-orientation (hetero-, bi- or homosexual) has been distinguished. Although it is believed that gender depends on the socio-environmental influences such as rearing, learning and individual choice, the biological factors are considered to be most important. This concept arises from recent study on patients with gender dysphoria syndrome (transsexualism). In intersexualism, in genetic men with disturbances of sexual differentiation of external genitalia because of the lack of testoterone production or action in peripheral tissues (male pseudohermaphroditism) or in genetic women with ambiguous genitalia because of the presence and action of androgens (female pseudohermaphroditism), a discordance between the formal sex (assigned after the birth) and the psychic gender may appear. In these individuals the legal sex established according to somatic and/or genetic sex at birth may be incompatible with their actual gender identity and role. The knowledge about gender identity is necessary at the decision of eventual (!) surgical correction of sex organs in patients with ambiguous genitalia. This decision should depend not on the expected, but on the actual gender identity of the individual patient. Meantime, early bilateral gonadectomy in patients with gonadal dysgenesis and male pseudohermaphroditism is an indication for life because of the highest risk of germ cell carcinoma.