Early effects of vinblastine and vincristine on the rat spermatogenesis: analyses by a new transillumination-phase contrast microscopic method.

Male sterility belongs to the recently recognized complications of cancer chemotherapy and has an increasing importance. Therefore, more information about the mode of action of anticancer drugs on mammalian spermatogenesis is needed. We have developed a technique based on transillumination of living, freshly isolated unstained rat seminiferous tubules, where the cells specifically killed by the drugs are recognized as dull zones. Early stages of cell degeneration can be rapidly analyzed by phase contrast microscopy of living cells. Because the transillumination technique, in addition, permits an accurate recognition of the segments of the seminiferous epithelial wave, the cells representing various stages of the mitotic and meiotic cell cycles during spermatogenesis can be isolated in living state for morphological analysis. Vinblastine and vincristine cause an arrest of mitotic and meiotic divisions to metaphase followed by cell death, which was more rapid after vincristine administration. Both alkaloids had a slight damaging effect on the pachytene spermatocytes. Large doses of both drugs primarily affected the Sertoli cells by destroying their microtubules and mitochondria. Vincristine specifically damaged the acrosomic system and the cytoplasmic bridges of the young spermatids.