Ultrastructure of abnormal boar spermatid: acrosomic fragmentation and vacuolization

The fine structure of acrosomic abnormalities such as fragmentation and vacuolization of boar spermatids was studied in 4 different breeds (Duroc, Hampshire, Landrace and Yorkshire). These abnormalities initially appeared from the cap phase of spermiogenesis. The acrosome did not consist of serial sac covering the hemispherical nucleus, but only of a large acrosomic vesicle containing a dense granule and several pieces of cleaved proacrosomic vesicles attached to the anterior half of the round nucleus. The abnormality was frequently observed in the sister cells connected with the intercellular bridge. In the same seminiferous tubules, there was another abnormality on the acrosomic vacuolization of limited membrane system. Multiple vacuoles or vesicles were seen in the apical part of the nucleus in the cap phase, and also in the lower part of the equatorial segment of the acrosome phase.