Sistema FMUSP-HC: Faculdade de Medicina da Universidade de São Paulo (FMUSP) e Hospital das Clínicas da FMUSPMENDONCA, B. B. deCOSTA, E. M. F.2023-02-092023-02-092017de Mendonca, B. B.; Costa, E. M. F.. Physiology of male gonadotropic axis and disorders of sex development. In: . TESTOSTERONE: FROM BASIC TO CLINICAL ASPECTS: SPRINGER INTERNATIONAL PUBLISHING, 2017. p.75-96.9783319460864; 9783319460840https://observatorio.fm.usp.br/handle/OPI/51050The hypothalamic-pituitary-testicular axis is activated in the third trimester of intrauterine life and during the neonatal period. Fetus testes differentiate by the end of the fifth embryonic week, before the gonadotrophs are functionally active. Therefore, GnRH deficiency does not affect male sexual differentiation. The 46,XY disorders of sex development (DSD) are characterized by atypical or female external genitalia, caused by incomplete intrauterine masculinization, in the presence or absence of Müllerian structures. 46,XY DSD result from decreased production of testosterone, decreased conversion of testosterone into dihydrotestosterone, or from impairment of their peripheral action. Under histological analysis, testicular tissue in patients with 46,XY DSD can be absent, partially or completely dysgenetic, or almost normal. Taking in account testosterone levels, the etiology of the 46,XY DSD can be classified into two large groups: low testosterone secretion and normal or high testosterone secretion. Most patients with DSD present with atypical genitalia and their sex assignment may be a complex procedure. The choice of male sex-of rearing in 46,XY babies with atypical genitalia is a challenging situation. The participation of a multidisciplinary team is essential during this process and the immediate identification of a molecular defect causing the disorder might aid in this decision. © Springer International Publishing Switzerland 2017.engrestrictedAccess46,XY DSDAMHFSHGnRHInhibinLHMale gonadotropic axisTestosteronebookPartCopyright SPRINGER INTERNATIONAL PUBLISHING10.1007/978-3-319-46086-4_3