Increased retention of spermatozoa in the reproductive tract of estrous rabbits after administration of prostaglandin F2 alpha immediately before insemination.

Two experiments were conducted to determine whether prostaglandin F2~ (PGF2a) administered to does immediately before natural or artificial insemination would increase the retention of sperm in the reproductive tract. The PGF2~ was injected intramuscularly at 200 /~g/kg of body weight. In the first experiment, 16 estrous does, eight injected intramuscularly with PG2a, were mated naturally and necropsied 3 hr later. In the second experiment, of 2 x 2 design, 32 estrous does, 16 injected with PGF2~, were inseminated artificially with either 34 or 102 million sperm and necropsied 3 hr later. After necropsy, each segment of the reproductive tract was flushed and sperm were counted. In each experiment, the PGF2 a treatment increased by at least threefold the number of sperm recovered from the oviducts, uterus, cervices and vagina, as well as the total number recovered from the reproductive tract. The PGF2a treatment reduced the normal loss of sperm from the reproductive tract during the first 3 hr after insemination. (