Ultrastructural changes in mouse testes following 60Co γ-irradiation

After an acute exposure to 550 rad of 60Co γ-rays, the ultrastructural changes in various cells of mouse testes were observed by transmission electron microscopy at different intervals. The results showed that spermatogonia, spermatocytes and spermatids were injured in decreasing order of severity. The surviving spermatogenic stem cells might play the role of repairing the germinal epithelium of seminiferous tubules. The Sertoli cells were slightly injured and able to phagocytize and digest the killed spermatogenic cells. No obvious morphologic changes were found in myoid cells and most Leydig's cells. Mitosis of the myoid cells occurred on Day 20 and Day 30 post irradiation. Thus the seminiferous tubules kept intact in structure, and high concentration of testosterone necessary for spermatogenesis was maintained. After irradiation three types of multinucleated giant cells appeared in the germinal epithelium, i.e. spermatogonic, spermatocytal, and spermatidal multinucleated giant cells. On the basis of morphological features of multinucleated giant cells, it is suggested that they might develop in the course of mitosis after irradiation as a result of nuclear division, unaccompanied by cytogenesis, of their predecessor cells. (author)