The Effects of Follicular Fluid on in Vitro Maturation of Bovine Follicular Oocytes

ABSTRACT

The present experiments were conducted to evaluate the effects of follicular fluid on maturation of bovine follicular oocytes. TC medium 199 seemed to be in adequate for this purpose since a high proportion (ranging 84.1. to 97.0%) of the oocytes were able to resume meiotic division in both media-with or without the addition of follicular fluid. This implies a possible similarity between TC medium 199 and follicular fluid with regard to the components initiating meiosis. Actually, TC medium 199 contains amino acids, vitamins and carbohydrates most of which are also found in follicular fluid. For this reason, the effect of follicular fluid on the ovum maturation was investigated by applying Krebs-Ringer bicarbonate solution (SECM), which was main1y composed of the salts, pyruvate and lactate. When the oocytes were cultured in SECM without the addition of follicular fluid, only 7-14% of them resumed meiotic division within 30 hours. However, when follicular fluid was added, the proportion of oocytes undergoing maturation was sharply increased to about 70%. Among the groups cultured in media containing different concentrations of follicular fluid, the proportion of the oocytes in meiosis remained constant, In pure follicular fluid, 87-89% of the oocytes showed enhancement of meiotic division. The presence of the follicular fluid contributed to a decrease in the production of degenerative oocytes. As a consequence it has been noted that addition of follicular fluid to the culture medium provides a more beneficial environment for cow oocytes. Meiotic division is initiated and production of degenerative oocytes is inhibited.