HUMAN SPERM BIOASSAY HAS POTENTIAL IN EVALUATING THE QUALITY OF CUMULUS-OOCYTE COMPLEXES

Human sperm bioassay is routinely used as a quality control check for the culture media. This is one of the three bioassays chosen by the Co llege of American Pathologists (CAP) for interlaboratory proficiency t esting to assess the standards of in vitro fertilization (IVF) and and rology laboratories. This study utilized sperm bioassay to assess the quality of cumulus-oocyte complexes (COCs) retrieved in IVF procedures . COCs, harvested from the female partner of IVF couples, undergoing i dentical ovarian stimulation protocols, were individually inseminated with the sperm of the corresponding male partner. Sperm motility in sp erm-COG cocultures were compared. Cocultures were established by insem inating the 103 COCs, retrieved from 18 IVF couples, with 1 x 10(5) to 2 x 10(5) sperm of the corresponding male partners of the couples. In all 18 cases, the sperm were prepared identically using the Percoll w ash method. The cocultures were maintained for 48 h but the oocytes we re removed immediately after the fertilization check (approximately 16 h). The motility of sperm in the cocultures and in the insemination s tocks were noted and 17 of 18 sperm stocks used for insemination had s imilar high preinsemination motility (90.2 +/- 5.0%). At 48 h the sper m motility had significantly decreased in the cocultures compared to t he insemination stocks; 52.7 +/- 19.9% versus 67.2 +/- 10.4%. There wa s no difference in the motility among the small, medium, and large COC s (56.4 +/- 24.6%, 52.5 +/- 17.9%, and 50.8 +/- 20.9%, respectively). In 45% of IVF cases, the motility in cocultures varied widely, falling below as well as above that of their corresponding insemination stock s. Furthermore, the sperm motility varied among the cocultures in both pregnant and nonpregnant patients but the extent of variation appears to be greater in the latter. The inter-COG coculture sperm motility v ariation most likely is due to the differences in the quality of cumul us-oocyte complexes.