In rodents, androgens induce the genitofemoral nerve to release calcitonin gene-related peptide, which produces rhythmic contractions of the gubernaculum, a ligament which connects the testis to the scrotum, but a similar mechanism has not been demonstrated in humans. Maldevelopment of the gubernaculum or deficiency or insensitivity to either AMH or androgen can, therefore, prevent the testes from descending into the scrotum. Some evidence suggests an additional paracrine hormone, referred to as descendin, may be secreted by the testes. In many infants with inguinal testes, further descent of the testes into the scrotum occurs in the first six months of life. This is attributed to the postnatal surge of gonadotropins and testosterone that normally occurs between the first and fourth months of life. Spermatogenesis continues after birth. In the third to fifth months of life, some of the fetal spermatogonia residing along the basement membrane become type A spermatogonia. More gradually, other fetal spermatogonia become type B spermatogonia and primary spermatocytes by the fifth year after birth. Spermatogenesis arrests at this stage until puberty. Most normal-appearing undescended testes are also normal by microscopic examination, but reduced spermatogonia can be found. The tissue in undescended testes becomes more markedly abnormal ("degenerates") in microscopic appearance between two and four years after birth. Some evidence indicates early orchiopexy reduces this degeneration. Pathophysiology
At least one contributing mechanism for reduced spermatogenesis in cryptorchid testes is temperature. The temperature of testes in the scrotum is at least a few degrees cooler than in the abdomen.
Terminology
Within the contexts of nephrology and dialysis, vascular access steal syndrome is also less precisely just called steal syndrome (for short), but in wider contexts that term is ambiguous because it can refer to other steal syndromes, such as subclavian steal syndrome or coronary steal syndrome. See also
Terms for anatomical location


== References ==