Impaired testosterone biosynthesis in cryptorchidism.

In an attempt to determine whether the production and synthesis of testosterone (T) by the testis is impaired by the cryptorchid state, the ability of the cryptorchid rat testis to form T was assessed at various time periods into adulthood after the surgical induction of cryptorchidism in the newborn period. The intratesticular T content of the descended testis rose from 0.3 ng/testis at 14 days of age to 71.2 ng/testis at adulthood (day 56); whereas in the cryptorchid testis, the values were 0.4 ng/testis and 2.0 ng/testis, respectively, at the same ages (P less than 0.001). For determination of the site of inhibition of T biosynthesis in the cryptorchid testis, the enzymatic activities (17 alpha-hydroxylase, 17,20-desmolase, and 17 beta-hydroxysteroid dehydrogenase) in the delta 4T biosynthetic pathway were measured. All these enzyme activities in the cryptorchid testis were inhibited at 56 days of age by about 80% when compared with the descended testis (P less than 0.01). These data suggest that cryptorchidism exerts a deleterious effect on the ability of the Leydig cells to synthesize T and may in part explain the abnormal morphology and resultant infertility seen in patients with cryptorchidism.