Uterine secretion from mares with post-breeding endometritis alters sperm motion characteristics in vitro

Uterine secretion was collected from five normal mares during estrus by the use of a tampon. In subsequent estrus cycles, mares were inseminated with 1x10(9) spermatozoa from a stallion of known fertility, and uterine secreti on was collected randomly at 6, 12, and 24 hours after insemination. All ma res had negative endometrial cytology before insemination. At the time of u terine secretion sampling, semen was collected from two stallions and exten ded with Kenney's extender to a concentration of 50x10(6) spermatozoa/mL. E xtended semen was diluted 2:1 with uterine secretion; semen extender; and c entrifuged uterine secretion (noncellular). Samples were kept at room tempe rature and sperm motion characteristics (corrected motility (CMOT), progres sively motile spermatozoa (PMS), and mean path velocity (MPV) were evaluate d using a computer-assisted semen analyzer every 40 minutes for a total of 4 hours. Sperm motion characteristics of spermatozoa were significantly bet ter when incubated in semen extender compared to uterine secretion (P < 0.0 5). The CMOT and PMS were significantly better in uterine secretion collect ed before, compared to after Al with the lowest values observed in samples collected at 12 hours after breeding (P < 0.05). Sperm motion characteristi cs of spermatozoa incubated in centrifuged uterine secretion was only sligh tly suppressed compared to spermatozoa incubated in semen extender, suggest ing that the altered motion characteristics were mostly due to the presence of polymorphonuclear neutrophils (PMNs) in the samples. It was concluded f rom this study that spermatozoa can survive in inflamed uterine secretion, but that sperm motion characteristics in vitro are altered. (C) 2001 by Els evier Science Inc.