[Light and scanning electron studies on the morphology of the vaginal plug in laboratory animals].

Serial sections of vaginal plugs of mice, rats, guinea pigs and hamsters (Cricetulus griseus) were studied by light microscopy as well as whole plugs and freeze-fractures by scanning electron microscopy. The vaginal plugs are encircled by a layer of superficial cells of the vaginal epithelium and consist of coagulated seminal fluid, containing irregular holes. The spermatoza are mainly localized inside bigger cavities. Scanning electron microscopic study of freeze-fractured plugs reveals, that this method gives useful information about the inner structure of spermatozoa tails.