TESTOSTERONE REGULATES APOPTOSIS IN ADULT HUMAN SEMINIFEROUS TUBULES IN-VITRO

In the present study an in vitro model was developed and characterized for evaluation of the role of apoptosis in adult human testes. The sa mples came from adult men undergoing orchidectomy for prostate or test icular cancer. Segments of seminiferous tubules were isolated and incu bated under serum-free conditions in the absence or presence of testos terone. Apoptosis was assessed by low mol mt DNA fragmentation (185-bp multiples) by use of 3'-end-labeled DNA, in situ end labeling, and mo rphological detection under light and electron microscopy. During the 4-h incubation, a 15-fold increase was seen in apoptotic DNA fragmenta tion. The extent of low mol wt DNA showed a time-dependent increase an d reached a 20-fold intensity in 24 h of incubation compared to the le vel at 0 h. Apoptosis was significantly suppressed by testosterone con centrations of 10(-7) and 10(-6) mol/L during the first 4 h of incubat ion. Apoptotic cells were identified mainly as spermatocytes and occas ionally as spermatids. We conclude that apoptosis is induced in human seminiferous tubules under serum-free conditions in vitro. That this a poptosis is suppressed by testosterone indicates that testosterone in the human male is a critical germ cell survival factor. The model crea ted in the present study provides a valuable tool for further investig ation of hormonal and gene regulation of human germ cell death and sur vival.