Effects of the induction of experimental cryptorchidism and subsequent orchidopexy on testicular function in immature rats.

Cryptorchidism surgically induced in 14-day-old rats, was allowed to persist until 35 days when one group was killed to assess testicular function. In a second group the cryptorchid testis was returned to the scrotum surgically (orchidopexy) and subsequently killed at 130 days. A third group remained persistently cryptorchid to 130 days, while in a fourth group two sham operations were performed at 14 and 35 days. At 35 days, cryptorchidism resulted in a significant decline in testis weight due to suppressed spermatogenesis. Sertoli cell function as measured by seminiferous tubule fluid (TF) production after unilateral efferent duct ligation and androgen-binding protein (ABP) production was significantly depressed in the cryptorchid group. Serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were significantly elevated with cryptorchidism but serum testosterone levels were unchanged. Although morphometric measurements showed no change in Leydig cells cross-sectioned area, in vitro human chorionic gonadotropin (hCG)-stimulated testosterone production was significantly increased in the cryptorchid group at higher hCG doses. Similar changes were found in cryptorchid testes at 130 days except that Leydig cell cross-sectional area was now significantly increased. Orchidopexy at 35 days restored spermatogenesis and fertility during test mating was not impaired. TF production, ABP accumulation and serum FSH levels returned to normal following orchidopexy.(ABSTRACT TRUNCATED AT 250 WORDS)