IMPACT OF PERCOLL(R) ON BOVINE SPERMATOZOA USED FOR IN-VITRO INSEMINATION

Percoll treatment of bovine frozen/thawed spermatozoa was identified a s the cause of low cleavage and blastocyst rates in our in vitro embry o production system. Percoll treatment of spermatozoa yielded very hig h, stable and repeatable results for many months of cleavage and blast ocyst rates of 83+/-5% (+/-SD) and 331+/-10%, respectively. This was f ollowed by a period with significantly lower cleavage and blastocyst r ates of 60+/-9% and 14+/-5%, respectively. In the last period, the res ults became even lower, with cleavage and blastocyst rates of 32+/-5% and 5+/-3%, respectively. These results were significantly different f rom those of the 2 previous periods. We were able to correlate precise ly these changes in outcomes to the introduction of new Percoll batche s. When compared with washed spermatazoa and under otherwise identical circumstances, the cleavage and blastocyst rates from spermatozoa tre ated with Percoll increased significantly from 33 to 73% and from 4 to 26%, respectively. We suggest that this adverse effect of Percoll is not due to Percoll particles per se, but may be ascribed to the effect of unbound polyvinylpyrrolidone (PVP) in the Percoll.