Acrosomal Cap Abnormalities of Sperm from Subfertile Bulls

Spermatozoa from a subfertile Jersey and from a subfertile Holstein and three of four sons were found to have abnormal acrosomal caps when examined in Giemsa-stained preparations. For the Holstein and two affected sons, the incidences of sperm with knobbed, ruffled, and incomplete acrosomes were about 5, 8 and 20%, respectively. Spermatids with acrosomal cap abnormalities were detected in PAS-stained testis tissue. Common defects, detectable as early as the time of nuclear elongation included spermatids with an acrosomic vesicle, a cyst of the acrosomic projection and invagination of the acrosomic projection into the nucleus. In semen from the Jersey bull, about 8% of the sperm had ruffled acrosomes. The significant correlation (r=:0.63) between the incidence of acrosomal cap abnormalities as determined in Giemsa-stained slides and by differential interference contrast microscopy suggests that fixation and staining did not induce masking artifacts. The implications of these apparently heritable abnormalities were discussed.