EFFICACY OF ORCHIDOPEXY ON SPERMATOGENESIS IN THE IMMATURE MUTANT TRANS-SCROTAL RAT AS A CRYPTORCHID MODEL BY QUANTITATIVE CYTOLOGICAL ANALYSIS

Objectives To determine whether cryptorchidism is a congenital malform ation and whether the impaired spermatogenesis in immature testes can be reversed by early orchidopexy, using the mutant trans-scrotal (T-S) rat which is normally masculinized but has cryptorchidism in 85% of m ales. Materials and methods First, T-S rats (six per group) with ectop ic testes destined to be undescended were investigated histologically at 4, 7 and 14 days after birth. Secondly, 12-day-old T-S rats were di vided into four groups which underwent different procedures, i.e. 1, w ith normally descending testes (normal control, 10 rats); 2, with unde scended testes (UDT) treated by orchidopexy (treated UDT, eight rats); 3, with UDT treated by a sham operation (sham-operated UDT, six rats) ; and 4, with UDT left untreated (untreated UDT, six rats). Thirty day s after operation the testicular anatomy was recorded; excised testes were examined histologically and different types of germ cells were co unted per tubule cross-section microscopically. Results There were no quantitative or morphological differences in the numbers of gonocytes, type-A sperm atogonia or Leydig cells in the seminiferous tubules bet ween normal and ectopic testes in the first 14 days after birth, Howev er, by 21 days of age spermatogenesis in the UDT had declined with tra nsformation from primary leptotene spermatocytes to spermatids. There were significantly more Leydig cells in the untreated UDT at 30 days t han in normal control testes. The impaired spermatogenesis in UDT was restored by early orchidopexy and there were significantly more semini ferous tubules at stage 3 (pachytene spermatocytes) and stage 4 (sperm atids) than in the untreated or sham-operated groups (P<0.001). Conclu sions These results show that in the T-S rat with cryptorchidism, the testicular damage is not a congenital malformation and can be reversed with early surgical correction.