Déterminisme sexuel, différenciation gonadique et identité du genre

Abstract

The description of the stages of sexual differenciation shows the initial intervention of the sexual chromosomes marked by the appearance of the Y chromosome on which “sex determining region of the Y chromosome” (SRY) is located. A cascade of genes occurs in a precise chronological order and contributes to the differentiation of a primitive gonad towards the anatomical structure of ovary or testis. The testis secretes testosterone, the main androgen, which enables penile development and testicular descent and contributes to the so-called masculine phenotype of the external genitalia. The testis also secretes a peptide hormone, the anti-mullerian hormone (AMH), which prevents the development of the tubes and uterus. This is how a man does not have a uterus. There is a tendency to consider that the absence of the Y chromosome conditions the development of internal genitalia in women and that the absence of testosterone maintains female-type genitalia. The recent identification of genes specific to the maintenance of ovarian architecture, assuring reproductive function, shows that in reality female development takes place through an active process and that the development of the genitals is associated with the production from estrogens by conversion or aromatization of androgens. Several authors have shown that in an individual there can be a discrepancy between somatic reality (sex) and psychic reality (gender role behavior) and thus open up the concept of gender identity. Thus, a number of men and women live at odds with their assigned sex and their gender identity. To date, no pathophysiological, hormonal or molecular support for gender identity disorders or dysphoria has been identified. The demand for care mainly concerns gender reassignment as in transsexuals. Its management is well codified with the establishment of a multidisciplinary consultation for the decision of hormonal and surgical treatment. In other cases, the demand for care is mostly absent. It often remains the consequence of the feeling of rejection of difference and of socio-cultural isolation.