Assay for Characterization of Human Follicular Oocyte Maturation Inhibitor Using Xenopus Oocytes 1

Abstract

Human follicular fluid from healthy mature Graafian follicles and from pathologic ovarian cyst fluid was inhibitory to progesterone-induced meiotic maturation of oocytes from the South African clawed toad, X. laevis. Human follicular fluid but not human serum, collected from the same individuals, demonstrated a linear dose-response inhibition on the maturation of oocytes in the Xenopus assay system. The human follicular and cyst fluids apparently contain oocyte maturation inhibitor (OMI) which was inactivated when subjected to a boiling water bath for 2 min. The OMI action was reversible in its inhibitory action. OMI''s ability to act directly on the oocyte was demonstrated by its inhibitory action on maturation in defolliculated oocytes. The inhibitory action of human OMI is not species-specific. Xenopus oocytes provide a simple, readily available, year-round bioassay material for testing follicular OMI.