ROLE OF SECRETED PROTEINS AND GONADOTROPINS IN PROMOTING FULL MATURATION OF PORCINE OOCYTES IN-VITRO

Experiments were designed to identify the extent to which follicle cel ls and hormones contribute to the developmental competence of porcine oocytes matured in vitro. Oocyte-cumulus complexes were collected from ovaries by dissection and cultured in 2 ml of TCM 199-based medium in 5% CO2 in humidified air at 38.5 degrees C. This basic maturation sys tem was supplemented, for either the first 24 hr only or for the 48-hr culture period, with 1) everted follicle shell alone, 2) gonadotrophi c hormones alone, or 3) both follicle shells and hormones. The effect of these treatments was evaluated on 1) meiotic maturation rates, 2) t he capacity of matured eggs to undergo activation and early cleavage, and 3) changes to the profile of proteins secreted into the culture me dium. The results showed that 1) supplementation with either follicle shell or hormones alone increased the rates of meiotic maturation over the nonsupplemented control group, and 2) combined follicle shell and hormonal supplementation yielded the highest rates for maturation, ac tivation, and cleavage but only when hormonal supplementation was remo ved after the first 24 hr of culture. Proteins of 30, 37, 45, and 46 k D, but of unknown function, were secreted during the first 24 hr into the culture medium in groups supplemented with follicle shells. The ad dition of hormones did not affect this pattern of secreted proteins. I t is possible that some secreted proteins may act to facilitate full m aturation of pig oocytes. (C) 1997 Wiley-Liss, Inc.