Factors affecting the composition of mare uterine fluid

The influx of protein and polymorphonuclear leucocytes (PMN) into the uterine lumen was examined at different intervals after intrauterine infusion of fluids. The intrauterine infusion of both phosphate buffered saline (PBS) and a solution of lipopolysaccharide (LPS) derived from Escherichia coli resulted in a biphasic influx of protein in the uterine flushings peaking three and six hours after infusion. LPS infusion caused an additional influx of protein at 24 hours. The initial influx of protein preceded a biphasic influx of PMN which peaked six and 24 hours after both infusions. Uterine flushings obtained following PBS and LPS infusion contained both serum-derived and uterine-specific proteins. To investigate whether the influxes were a general response to reproductive mucosal stimulation, several regions of the reproductive tract were subjected to physical manipulation. Results suggested that these influxes were initiated chiefly by stimulation of the cervical and, or, uterine region.