Timing of Shedding and Disintegration of Cytoplasmic Droplets from Boar and Goat Spermatozoa

The timing of shedding and disintegration of cytoplasmic droplets from boar and goat spermatozoa was determined. More than 90% of spermatozoa from the cauda epididymidis and ductus deferens had a droplet each at the distal region of the middle piece in both species. In boars, the droplets were still observed in 97% of spermatozoa immediately after ejaculation. After 1 min of ejaculation, however, the percentage of spermatozoa without the droplet greatly increased to 65%, with no significant changes thereafter. Moreover, most of the free droplets shed from spermatozoa had already disappeared after 1 min of ejaculation. In goats, most spermatozoa (90%) had no droplet even immediately after ejaculation, and the rate of free droplets remaining in the semen was 63%. However, within 2 min of ejaculation, the rate of free droplets remaining in the semen dropped to 8%. These results indicate that shedding of cytoplasmic droplets from boar spermatozoa and their disintegration occur within 1 min after ejaculation. They also suggest that droplets are shed from most of goat spermatozoa during their transit through the urethra and/or immediately after ejaculation, and that their disintegration occurs within a few minutes after ejaculation.