A follicular fluid factor inhibiting Xenopus oocyte maturation

A factor was isolated from bovine follicular fluid (FF) that blocked progesterone-induced maturation of Xenopus oocytes. The factor was purified by ultrafiltration through PM-10 membrane, gel filtration on Sephadex G-25 column, gel permeation chromatography on Superose 12 column and reversed-phase HPLC on Partisil ODS-3 column. The active factor is a peptide with an estimated Mr of 8000 and it effectively blocked progesterone-induced maturation of Xenopus oocytes at a concentration of 100 micrograms/ml. On the other hand, it did not influence the spontaneous maturation of isolated cumulus-enclosed or denuded mouse oocytes. The present findings suggest that the FF factor may be an inhibitor or antagonist of progesterone action.