Steroid production by the cumulus: relationship to fertilization in vitro.

Abstract

Insemination media were collected from 92 follicles of 14 patients stimulated to undergo oocyte retrieval for in-vitro fertilization. Levels of progesterone and oestradiol in the insemination drops were assayed, corrected for carry-over from follicular fluid and volume and expressed as production per microgram of protein in the cumulus. Significantly higher progesterone production per unit protein was associated with oocytes which fertilized in vitro (P less than 0.02). Oocytes fertilizing with subsequent fragmentation or degeneration showed progesterone levels significantly higher than oocytes fertilizing normally (P less than 0.05). Polyspermic oocytes (n = 3) were associated with very high levels of progesterone production but were not significantly different due to the low numbers. Oestradiol production per unit protein was significantly greater in oocytes which fertilized normally than in those which degenerated (P less than 0.05). The protein content of cumuli whose oocytes fertilized appeared to be significantly lower than those which did not (P less than 0.05). These results probably reflect the maturity of the follicle, although direct actions of cumulus products upon the gametes cannot be ruled out.