Morphological changes of mouse spermatozoa in uterus as revealed by scanning and transmission electron microscopy.

Submicroscopic alterations occurring in mouse spermatozoa during their sojourn into the female reproductive tract--as revealed by Scanning Electron Microscopy and Transmission Electron Microscopy using ruthenium red as marked for glycosaminoglycans--are described in the present investigation. The results show that the surface of the plasma membrane covering the acrosomal region of the spermatozoa found in the uterus--at different intervals of time after copulation (between 10 minutes up to 20 hrs)--are provided with an increasing number of granules and small vesicles. Some of the surface structures appear gradually leading to perforation of discrete areas of plasma membrane in regions corresponding to acrosomal areas covering the head of spermatozoa. Similarly ruthenium red preparations, show a significant decrease of glycosaminoglycans and their sialic acid moieties, which specifically precede further vesiculation and perforation of the sperm plasma membrane covering the same acrosomal regions.