Concentrations of prostaglandin F2 alpha in the pig oviductal fluid

Oviductal fluid was continuously collected from cycling, unrestrained gilts during late proestrus, standing heat and early luteal phase. Collection was performed via cannulae exteriorized to single vented collection tubes attached to the skin. In some cases one of the oviducts was transected at isthmic level to compare fluid production rates with those of the contralateral intact tube. A consistently elevated fluid production was observed during proestrus and standing heat, being highest at the second day of the cycle, thereafter decreasing. No significant differences were seen between daily collection rates from right or left nor between intact and isthmic transected oviducts. Levels of PGF2 alpha were determined by RIA in the collected samples. Relatively large day to day fluctuations in PGF2 alpha values were evident and a consistent relationship was found between concentration and the stage of the estrous cycle. The highest PGF2 alpha mean values (up to 50 ng/ml fluid) were also found on the second day of standing heat, concurrently periovulatory.