Transport and Phagocytosis of Fresh Versus Aged Rabbit Sperm

Abstract

Published research indicates that few of the sperm deposited in the female tract are recovered after insemination. Experiments were performed in rabbits to determine if sperm recovery could be improved by intensive flushing, and to examine leucocytic response as a factor affecting recovery. Freshly ejaculated and washed sperm were compared with sperm aged for 10 to 12 h in vitro prior to insemination. More aged sperm (54%) were recovered from the uterus than fresh sperm (36%) within 10 to 15 min of uterine deposition. Use of whole semen instead of washed sperm reduced recovery of both types of sperm (33 to 37% recovery). Increasing concentrations of Triton X-100 and multiple flushes increased recovery of fresh sperm, but not of aged sperm. Only 6.6% of the aged sperm and 11.5% of the fresh sperm were engulfed by neutrophils after 12 h in ligated uteri, and many sperm were unaccounted for. A breakthrough in recovery was achieved by developing a method to solubilize neutrophils, leaving sperm heads intact. This increased recovery of sperm held for 12 h in the female from 48% before to 93 to 95% after neutrophil dissolution. This technique will enhance studies involving sperm interactions in the female.