Distribution and Morphology of Fresh and Frozen-Thawed Sperm in the Reproductive Tract of Gilts after Artificial Insemination

Abstract

Gilts [68] were inseminated intracervically with equal numbers of fresh or frozen boar sperm. Sperm were recovered from various segments of the reproductive tract at 2, 8 and 24 h after insemination. More sperm were recovered from the uterotubal junction and uterus of gilts inseminated with fresh semen than of gilts inseminated with frozen semen (P < 0.005). In the oviducts, no differences were found at 2 or 8 h in the numbers of sperm in gilts receiving fresh or frozen semen, however, at 24 h, markedly fewer oviductal sperm were recovered from gilts inseminated with frozen semen. Sperm were recovered from various segments of the reproductive tract at 4 or 14 h after insemination and the number, motility and acrosome morphology of the sperm were determined. More sperm were recovered from the oviductal, uterotubal and uterine segments of the reproductive tracts of gilts inseminated with fresh semen than in gilts inseminated with frozen semen (P < 0.005 for each segment). The percentage of motile sperm in the oviduct was significantly lower in gilts inseminated with frozen semen than in gilts inseminated with fresh semen. The percentage of sperm acrosomes with a normal apical ridge (NAR) was significantly higher in all segments of the reproductive tract in gilts inseminated with fresh semen than in gilts inseminated with frozen semen (P < 0.005). A definite trend for a higher relative percentage of NAR acrosomes in each segment of the tract progressing cranially indicates that a degree of sperm selection occurred at the utertubal junction. The number of polymorphonuclear leukocytes in uterine flushings was similar for gilts inseminated with fresh or frozen semen (P > 0.10). Phagocytosis of sperm was occurring in gilts by 2 h after insemination of fresh and frozen semen. Phagocytosis was probably not responsible for the preferential removal of frozen sperm in the first few h after insemination.