APOPTOSIS-LIKE CELL-DEATH IN EXPERIMENTALLY-INDUCED CRYPTORCHIDISM INADULT MICE

In order to elucidate the mechanism of germ cell degeneration in exper imental cryptorchidism, we examined the testes of adult mice from a mo rphological standpoint. Adult ICR mice were made cryptorchid either un ilaterally or bilaterally. in some mice, testes were surgically replac ed back into the scrotum at 2 months after induction of cryptorchidism to observe the regenerative process. Morphological changes of cryptor chid and replaced testes have been studied by light and electron micro scopy. Testes were also examined by the TUNEL (TdT-mediated dUTP-bioti n nick end labelling) method to evaluate whether the degenerative cell s, spermatocytes and spermatids, were dying by apoptosis or by any oth er process(es). At 8 weeks after the induction of cryptorchidism, the seminiferous epithelium consisted only of Sertoli cells, spermatogonia , and some spermatocytes of early meiotic stages. Soon after the repla cement of testes to the scrotum, most of the seminiferous tubules resu med spermatogenic processes. Many degenerating cells, especially the s permatocytes, showed condensation of the nucleus and cytoplasm in cryp torchid testes. Although the cytoplasm was markedly eosinophilic under a light microscope to imply condensation of the cytoplasm, the extent of the condensation was not as pronounced under an electron microscop e as reported in previous publications. The cytoplasm showed no expans ion. By the TUNEL method, many of the degenerating cells, mainly the s permatocytes, have been shown as undergoing apoptosis. These data prov ide evidence that at least some of the cells die by apoptosis, or by a process similar to apoptosis.