CORRELATIONS BETWEEN CHEMICAL-PARAMETERS, MITOGENIC ACTIVITY AND EMBRYOTROPHIC ACTIVITY OF BOVINE OVIDUCT-CONDITIONED MEDIUM

To establish parameters predicting the quality of bovine oviduct epith elial cell-conditioned media, we compared media conditioned by oviduct cells from cows at Day 2 (n=3) and Day 15 (n=3) of the estrous cycle. In addition, we tested the influence of time of conditioning. Media w ere evaluated for their embryotrophic activity using a cumulus cell co -culture system as a control. The same media were tested for their mit ogenic activity on NIH 3T3 cells and for chemical parameters, includin g total protein, and de novo synthesized protein as well as for concen trations of glucose, lactate and ammonium. Analysis of variance did no t reveal a significant effect by stage of the estrous cycle on the emb ryotrophic activity of conditioned media. However, there was a signifi cant effect by time of conditioning on the proportion of 5- to 8-cell embryos (P<0.01) and of blastocysts and hatched blastocysts (P<0.05). None of the conditioned media (19 to 31% blastocysts) was superior to the cumulus cell co-culture system (32% blastocysts). In the condition ed media, the proportion of 5- to 8-cell embryos correlated positively with mitogenic activity on 3T3 cells (r=0.64; P<0.05), whereas the pr oportion of blastocysts was not significantly correlated with this par ameter. In summary, our results provide evidence for an effect of time of conditioning on embryotrophic activity of oviduct epithelial cell- conditioned media. The fact that mitogens for NIH 3T3 cells affect the proportion of 5- to 8-cell embryos but not of blastocysts suggests di fferent culture requirements for early and late preimplantation stage development of bovine embryos. (C) 1997 by Elsevier Science Inc.