Ultrastructure of the seminiferous epithelium of ethyl methanesulphonate-treated mouse.

Ethyl methanesulphonate (EMS) is a mutagenic alkylating agent that induces marked elevations of sperm abnormalities in mice. In this paper, we report the ultrastructural findings on the morphology of the seminiferous epithelium of mice resulting from EMS administration. Eight- to twelve-weeks-old male mice were injected intraperitoneally with EMS at 200 mg kg(-1) body weight daily for five consecutive days. Analysis of smears of epididymis and semi-thin sections of testes revealed that the more suitable specimens for the ultrastructural analysis were tissues of mice killed at the third week, following EMS administration. At this time, the spermatid was the damaged cell type. Abnormalities were mainly observed in the morphology of the nucleus, the acrosome, chromatin distribution and in the arrangement of the cytoplasmic microtubules, and binucleated spermatids were also observed. EMS has the capacity to penetrate the blood-testis barrier, and thus it can damage post-meiotic spermatogenic cells. However, morphological abnormalities could be the consequence of damage exerted on the differentiated spermatogonia stage, the most sensitive spermatogenic cell to the action of chemical agents or drugs. Our findings contribute to elucidate the action mechanism of the damage exerted by EMS administration on the germinal male cells.