Effect of follicular fluid supplementation on the in vitro development of human pre-embryos.

Objective: To evaluate the value of supplementing a standard culture medium with 10% heat-inactivated mature follicular fluid (FF).

Design: Prospective randomized study evaluating the in vitro development of nontransferred, nonfrozen human pre-embryos in three culture conditions from day 3 to day 8 postfertilization. Preliminary evaluation by RIA and electrophoresis of factors responsible for these results.

Results: Ten percent mature FF supplementation of Inra Menezo (B2 medium) was associated with a significantly higher proportion of human pre-embryos reaching the morula (95% versus 72% with 10% maternal serum, P = 0.04) and the blastocyst stage (50% versus 11% with B2 alone, P = 0.02). The concentration of insulin-like growth factors I and II did not differ significantly between serum and mature FF-supplemented medium. Protein electrophoresis showed a difference of two bands corresponding to a molecular weight of 17,000 present in the serum and not in the FF-supplemented medium.

Conclusion: Culture medium supplementation with 10% mature FF is associated with a significantly higher proportion of pre-embryos reaching the morula and blastocyst stage. The observed difference could be explained by the presence of a low molecular weight (17,000) embryotoxic factor contained in the serum-supplemented medium.