Flagellum abnormalities of spermatozoa in seminiferous tubules after a short term vasectomy.

Electron microscopic observation was performed to examine whether spermiogenesis in the hamster might be affected by a short term vasectomy. When viewed by light microscopy, spermiogenesis was temporarily inhibited at 2 weeks, though to a limited extent among individuals, and had apparently recovered to the control level at 4 and 8 weeks after vasectomy in all hamsters. It was revealed at the electron microscopic level that mature spermatozoa with an abnormal flagellum were intermingled among numerous normal spermatozoa. The flagellum of the mature spermatozoa was composed of four different components: a mitochondrial sheath, outer dense fiber, fibrous sheath and axoneme. Abnormalities of the mitochondrial sheath were of three types: its discontinuity, displasia and deformation. The appearance of these abnormalities increased with the time after vasectomy and finally reached 52% as the highest value at 8 weeks. Additional noteworthy findings were the bisectioning of the outer dense fibers 2, 4 and 7, the fusion of two or three fibers, and the partial deletion of the fibrous sheath. These defects were characteristic in the vasectomized hamsters. Possible correlating microenvironmental factors are discussed as to how these abnormalities of the four flagellar components occur in the vasectomized hamsters.