EFFECT OF SHEEP AND HUMAN FOLLICULAR-FLUID ON THE MATURATION OF SHEEPOOCYTES IN-VITRO

This study examines the effect of sheep and human follicular fluid on the in Vitro maturation (IVM) of sheep follicular oocytes. Oocyte cumu lus complexes recovered post mortem were matured for 24 to 26 h at 38. 6 degrees C, 5% CO2 in air, in TCM-199 bicarbonate medium supplemented with 20% fetal calf serum(FCS) and, where slated, with maturation hor mones, including FSH (5.0 ug/ml), LH (5.0 ug/ml) and estradiol (1 ug/m l), or with sheep follicular fluid recovered from large (>5mm) or smal l (2 to 5mm) ovarian follicles post. mortem, or with human periovular follicular fluid obtained during routine IVF procedures. The matured o ocytes were then denuded, and their maturation stage and developmental capacity were assessed by in vitro fertilization (IVF) and culture (I VC). It was found that inclusion of sheep or human follicular fluid or hormone supplements in the NM media more than doubled the number of o ocytes completing maturation (FCS alone 33%, compared with 76.2% for m aturation hormones, 84.2% for fluid from large and 69.6% for fluid fro m small sheep follicles and 82.6% for human follicular fluid), and sig nificantly increased fertilization rates (FCS alone 51.6%, compared wi th 71.9% for maturation hormones, 78.4% for fluid from the large and 7 5.7% for fluid from small sheep follicles and 73.1% for human follicul ar fluid) without discernible adverse effects on the development of th e cleaving embryos to the morula or blastocyst stage in culture. Omiss ion of FCS and supplements from the IVM medium resulted in a marked re duction (56%) in the number of oocytes maturing. This reduction could be offset to a large part, but not completely, by inclusion of human f ollicular fluid or human follicular fluid plus LH (5 ug/ml) in the med ium. The results of this study show that addition of sheep or human fo llicular fluid to maturation medium can enhance rather than inhibit th e maturation and fertilizability of sheep follicular oocytes in vitro.