A comparative study of the effects of non-union of testis and epididymis and cryptorchidism on testicular development and spermatogenesis in the rat.

Malunion of testis and epididymis is a congenital anomaly of human undescended testicles which may be of considerable clinical importance. In an experimental model in rat the effects of early disconnection of testis and epididymis (16 days) on testicular development have been testis and puberty. The results are compared with corresponding effects of cryptorchidism and sham-operation. The testes were weighed, and the relative proportions of haploid, diploid and tetraploid cells were quantified by DNA flow cytometry. The histology was evaluated by light and electron microscopy. The non-union operated testes showed a close to normal weight development until about 40 days of age, whereafter a decline occurred. The progression of the maturation division was only slightly reduced at 30 and 37 days of age, but later the spermatogenesis was significantly inhibited. At 58 days of age the maturation division had practically ceased in non-union operated testes. In cryptorchid animals the onset and progression of maturation divisions were almost totally depressed, and only traces of haploid cells were seen in some specimens. The transient increase in tetraploid cells, reflecting primary spermatocytes seen at about 30 days during normal testicular development, was neither depressed in non-union operated nor in cryptorchid animals. This indicates that the major block in spermatogenesis in both situations is at the stage of the primary spermatocytes. At 58 days of age the testicular histology was similar in non-union operated and cryptorchid testicles with many tubular sections showing only Sertoli cells. Scattered and partly degenerated germinal cells were seen in some sections. No histological signs of increased intratubular fluid pressure were detected, suggesting that pressure atrophy is not decisive for the reduced spermatogenesis in non-union operated gonads.