Journal of Pediatric Surgery-Sponsored Fred McLoed Lecture. Undescended testis: the underlying mechanisms and the effects on germ cells that cause infertility and cancer.

Testicular descent is a complex morphological process that occurs in at least 2 stages, with different hormonal control. Insl3 controls the first step of gubernacular enlargement, although the abnormality long gubernacular cord in persistent Műllerian duct syndrome remains unexplained. Androgens control inguinoscrotal migration, which may be triggered by local signalling from the mammary line, and which requires the genitofemoral nerve. However, there is still much to learn about this phase, which when abnormal frequently leads to cryptorchidism. Orchidopexy is being recommended in the first year of age, because increasing research suggests that the stem cells for spermatogenesis form between 3 and 9 months, with surgery aiming to permit this normally, although this is not yet proven. Acquired cryptorchidism is now becoming accepted and is likely to be caused by inadequate elongation of the postnatal spermatic cord. It is not yet known whether orchidopexy is always needed, as this remains controversial.