Male sex differentiation is driven by 2 hormones, testosterone and anti-müllerian hormone (AMH), responsible for the regression of müllerian ducts in male fetuses. Mutations inactivating AMH or its receptor AMHRII lead to the persistent müllerian duct syndrome (PMDS) in otherwise normally virilized 46,XY males. Our objective was to review the clinical, anatomical, and molecular features of PMDS based upon a review of the literature and upon 157 personal cases. Three clinical presentations exist: bilateral cryptorchidism, unilateral cryptorchidism with contralateral hernia, and transverse testicular ectopia. Abnormalities of male excretory ducts are frequent. Testicular malignant degeneration occurs in 33% of adults with the disorder, while cancer of müllerian derivatives is less frequent. Fertility is rare but possible if at least one testis is scrotal and its excretory ducts are intact. Eighty families with 64 different mutations of the AMH gene have been identified, mostly in exons 1, 2, and 5. AMHRII gene mutations representing 58 different alleles have been discovered in 75 families. The most common mutation, a 27-bp deletion in the kinase domain, was found in 30 patients of mostly Northern European origin. In 12% of cases, no mutation of AMH or AMHRII has been detected, suggesting a disruption of other pathways involved in müllerian regression.

Anti-Müllerian hormone (AMH) produced by fetal Sertoli cells is responsible for regression of Müllerian ducts, the anlage for uterus and Fallopian tubes, during male sex differentiation. A member of the transforming growth factor-beta superfamily, AMH signals through two transmembrane receptors, type II which is specific and type I receptors, shared with the bone morphogenetic protein family. Mutations of the AMH and AMH receptor type II (AMHR-II) genes lead to persistence of the uterus and Fallopian tubes in males. Both conditions are transmitted according to a recessive autosomal pattern and are symptomatic only in males. Affected individuals are otherwise normally virilized, undergo normal male puberty; and may be fertile if testes, tightly attached to the Fallopian tubes, can be replaced in the scrotum. Approximately 85% of the cases are due, in similar proportions, to mutations of the AMH or AMHR-II gene. The genetic background does not influence the phenotype, the only difference is the level of circulating AMH which is normal for age in AMHR-II mutants and usually low or undetectable in AMH gene defects. This is due to lack of secretion, explained by the localization of the mutations in critical regions, based on the assumed 3D structure of the molecule. Similarly, lack of translocation to the surface membrane is responsible for the inactivity of AMHR-II molecules bearing mutations in the extracellular domain. In 15% of cases, the cause of the persistent Mullerian duct syndrome is unknown and could be related to complex malformations of the urogenital region, unrelated to AMH physiology.

Anti-Müllerian hormone (AMH) has been detected by RIA in the follicular fluid of mature bovine ovaries and in incubation medium of bovine granulosa cells. Purification of AMH from two independent batches of follicular fluid was achieved with a yield of 11% and 15% respectively. Both ovarian and control testicular AMH produced near-complete regression of fetal rat Müllerian ducts exposed to it in culture at a final concentration of 200-300 mU/ml and were recognized by the same monoclonal and polyclonal antibodies. These findings indicate that adult mammalian granulosa cells are capable of producing immunoreactive and bioactive AMH at a rate apparently similar to that already demonstrated for mature Sertoli cells and add yet another item to the homologies reported between male and female somatic gonadal cells.