Testicular damage by high doses of vitamin B6 (pyridoxine) in rats: a light and electron microscopical study.

Male Wistar rats were administered daily intraperitoneal injections of 125, 250, 500, and 1000 mg/kg/day of vitamin B6 for 2 and 6 weeks and the histogenesis of the testicular damage was investigated. A reduction of germ cells was not prominent in the 2-week groups, whereas a delay in spermiation, degeneration of elongated spermatids, and Sertoli cell alterations were observed in the 500- and 1000-mg groups, although generally, these were relatively mild. Ectoplasmic specializations (ES), tubulobulbar complexes, and endoplasmic reticulum (ER) in the apical processes of Sertoli cells were irregularly arranged and their disappearance was also retarded. The Sertoli cell cytoplasm was often retracted and condensed. In the 6-week groups, no histological change in the testis was noted with the 125-mg dose. The retardation in spermiation and Sertoli cell alterations similar to those in the 500-mg dose 2-week group were observed in the 250-mg group. In the 500- and 1000-mg groups, germ cells were generally degenerated and markedly reduced in number. Multinucleate germ cells were mingled with anisocytotic germ cells, and openings of intercellular bridges were occasionally found. Sertoli cells also showed more severe alterations, such as focal disappearance of ES in earlier than ordinary stages, marked dilation of the ER, and markedly condensed or electron-lucent cytoplasm. These results suggest that the Sertoli cell damage may induce diverse germ cell degeneration in which retardation of spermiation occurs first.