Fate and functional integrity of fresh and frozen-thawed ram spermatozoa following intrauterine insemination.

Ewes in a synchronized oestrus were inseminated (intrauterine) with fresh and frozen-thawed spermatozoa and the spermatozoa were either recovered from each section of the reproductive tract after the animal was killed (Experiments 1a and 1b) or after they were voided from the cervix (Experiment 2). In Experiment 1a, only 1.2+/-0.27% of the original inseminate was recovered. Placing a ligature at the base of the uterine horn in Experiment 1b led to the recovery of 3.0+/-0.33% of the original inseminate, located mainly in each uterine horn (33.1+/-5.48%), and each isthmic and ampullary region of the oviduct (2.9+/-5.48% and 4.0+/-5.48%, respectively). A higher proportion of spermatozoa recovered from the isthmus were uncapacitated when observed by chlortetracycline staining than those recovered from the uterus (26.4+/-1.92% and 15.6+/-1.92%, respectively, P<0.05). Experiment 2 showed that large proportions of spermatozoa were voided from the tract through the vagina, with similar numbers of fresh and frozen-thawed spermatozoa lost from the tract. However, frozen thawed spermatozoa were lost at a faster rate than fresh (P<0.05) and with a more advanced membrane state (66.8+/-1.30% and 53.2+/-1.30% were acrosome reacted respectively; P<0.001). Large numbers of recovered spermatozoa had lost their tails, with frozen-thawed spermatozoa more susceptible to tail loss than fresh spermatozoa (55.0+/-0.96% and 45.5+/-0.96% respectively; P<0.05).