Could testicular descent in humans be promoted by direct androgen stimulation of the gubernaculum testis?

Gubernaculum testis and androgens play an important role in physiologic testicular descent. A direct androgen stimulation of the gubernaculum is only possible in the presence of specific receptors, which have not yet been demonstrated. We have determined the androgen-binding capacity in 61 samples of gubernaculum testis from 48 patients, 34 samples belonging to patients with maldescended testes. In 43 out of 61 instances we found androgen binding with values up to 72 fmol/mg, with a mean of 13.08 fmol/mg. In 27 samples from patients with a deep scrotal positioned gonad the mean androgen-binding capacity was 18.74 fmol/mg. In 10 samples from patients with a gonad in the proximal scrotum and 19 patients with epifascial ectopy or a low inguinal position the mean androgen-binding capacities decreased progressively to 9 fmol/mg and 5.95 fmol/mg. In the 5 samples from patients with high inguinal or abdominal testes the binding capacity of 17.8 fmol/mg did not significantly differ from the value obtained in the samples of the normal-positioned gonads, suggesting that transabdominal descent is probably not androgen-dependent. We divided the probes into receptor status positive for a binding capacity higher than or equal to 10 fmol/mg, and receptor status negative for a binding capacity under 10 fmol/mg. 63% of the samples from patients with scrotal positioned testes were receptor status positive, 85% of the samples belonging to patients with maldescended testes were receptor status negative. Receptor status was negative in patients with high scrotal, epifascial or low inguinal and high inguinal or abdominal testes in 90%, 95% and 40% of the samples respectively. Immunohistochemical examination of 10 samples showed small cell groups with stained nuclei in 2 out of 5 patients with normal-positioned testes. All other samples were negative. These findings prove that hormone binding was accomplished by specific intranuclear receptors. These findings allow for the first time the hypothesis of a direct androgen stimulation of the human gubernaculum testis. The probable mechanism is an increase in mucopolysaccharides leading to a swelling of the gubernaculum, dilating the inguinal canal and promoting testicular descent. Although certainly a multifactorial process, quality and quantity of androgen receptors would influence the extent of transinguinal testicular descent.