A specific oligoteratozoospermia in a bull: The sperm tail stump defect

The first known case in the United States of a bull with the sterilizing oligoteratozoospermia known as “sperm tail stump defect” is reported. Ejaculates of semen were characterized by a watery appearance, extremely low sperm concentrations, sperm akinesia, and 100% abnormal spermatozoa. Different degrees of partial tail development were observed. The most common abnormalities were a short midpiece remnant or a cytoplasmic droplet-like rounded body replacing the midpiece and tail. Also, a high percentage of sperm head abnormalities were found. Testicular histology revealed seminiferous tubules with a low rate of spermatogenesis. Elongation of the spermatids did not proceed normally and no normal tail development was observed.