ABSTRACT
The complex sequential process of normal sex determination and differentiation is regulated by at least 50 different genes located on sex chromosomes and autosomes that act through distinct mechanisms, including organizing factors, gonadal steroid and peptide hormones, and target-specific tissue receptors (Grumbach and Conte, 1999). In brief, normal sex development consists of 3 sequential processes (Forest, 1995), the first being the genetic sex determination by the sex chromosome constitution in the zygote at the time of conception. Thereafter, the genetic information determines whether an undifferentiated gonad differentiates into either a testis or an ovary (gonadal or primary sex). Finally, the phenotypic sex results in male differentiation, an active process resulting from testicular secretions. Among these hormones, the anti-Müllerian hormone (AMH) produced by the Sertoli cells, inhibits the Müllerian ducts, whereas testosterone (T) produced by the Ley dig cells, is responsible for stabilization of the Wolffian ducts, and via its transformation into dihydrotestosterone (DHT), is also responsible for virilization of the external genitalia. Consequently, the genital primordia are irreversibly committed to the female state in the absence of testis (Forest, 1995).
