Biochemical Compositions of Follicular Fluid and the Effects of Culture Conditions on the In Vitro Development of Pig Oocytes

The aims of this study were, firstly, to analyze the biochemical compositions of serum and follicular fluid (FF) from prepubertal gilts after PMSG (1,000 IU) treatment. The concentrations of total proteins, lipids, cholesterol, glucose and sex hormones (progesterone, P4; estradiol-17β, E2; testosterone, T) were measured. Secondary, the effects of porcine FF (pFF) addition (40% and 100%) in IVM media and different culture conditions [Exp. 1: mBMOC-2+20% porcine serum (PS), fresh IVM medium, filtered IVMconditioned medium, or rabbit oviducts; Exp. 2: mBMOC-2+20%PS or stepwise medium replacement procedures (SMRP) cocultured with or without cumulus cells] on the in vitro development (IVD) of porcine oocytes were also examined. Results showed that no significant differences were found in total protein levels between serum and pFF from different sizes (large, >7 mm; medium, ~5-7 mm; small, <3-5 mm) of follicles (75-85 and 49-90 mg/dl; p>0.05). Total lipid concentrations remained constant in serum (395-472 mg/dl), and reduced significantly in the pFF from large follicles (287 mg/dl) at 132 h after PMSG treatment when compared to those at other time points (441-480 mg/dl). Basal cholesterol levels in serum and pFF at 12 h were similar (153-161 mg/dl), but increased at 36 h (186197 mg/dl). Basal P4 and E2 levels in serum (0.1 ng/ml and 5.5 pg/ml) were low, but increased from 0.34 ng/ml and 12.13 pg/ml at 24 h to 0.81 ng/ml and 61.70 pg/ml at 98 h, respectively, after PMSG treatment (p<0.05). P4 levels increased linearly in pFF from large follicles during 12 through 132 h (138-1,288 ng/ml). A similar increase was also observed in E2 levels (22-730 pg/ml) before 60 h post PMSG treatment, and then dropped afterwards (730-121 pg/ml). The development of the oocytes fertilized in 40% pFF-medium was greater than that in 100% pFF-medium group without gonaodtropin addition (31% vs 10%, p<0.05). However, both were lower than those in mBMOC-2+20%PS and in rabbit oviducts (p<0.05). When cocultured with cumulus cell monolayers, a greater cleavage rate was observed in the group cultured in filtered IVM-conditioned medium than the SMRP group (36% vs 18%, p<0.05). A similar phenomenon was also observed in the culture without cumulus cell monolayers (33% vs 19%, p<0.05). It is concluded that neither the fresh IVM nor filtered IVM-conditioned medium has positive effect on the IVD of oocytes. Coculture with cumulus cell monolayers and the SMRP were not beneficial to the development of IVF pig oocytes. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 10 : 1403-1411)