HEAT-STRESS CAUSES TESTICULAR GERM-CELL APOPTOSIS IN ADULT MICE

An investigation was undertaken to determine whether the germ-cell los s associated with exposure of the testis to abdominal temperature occu rs by apoptosis. Using an adult-mouse model of experimental unilateral cryptorchidism, it was observed that DNA fragmentation, consistent wi th apoptosis, was observed on day 6 in the cryptorchid testis, with su bsequent loss of testicular weight, histologic evidence of germ-cell l oss, and histochemical staining of apoptotic germ cells observed on da y 7. Vacuolization of the germinal epithelium and the appearance of mu ltinucleated giant cells was noted synchronously with the onset of ger m-cell loss. Histochemical staining for apoptosis was noted most frequ ently among the primary spermatocytes and round spermatids. These resu lts indicate that the testicular germ-cell loss observed with exposure to abdominal heat stress occurs by apoptosis. Further investigation o f the biochemical mechanisms involved in testicular apoptosis may prov ide strategies to address a variety of male reproductive issues such a s contraception and infertility.