288EFFECTS OF OVIDUCTAL EPITHELIAL AND CUMULUS CELLS ON FERTILIZATION AND EMBRYO DEVELOPMENT OF PIG OOCYTES IN VITRO

Abstract

This study was carried out to investigate the effect of adding porcine oviductal epithelial cells (POEC) and also the presence of cumulus cells during in vitro fertilization on fertilization rate and subsequent embryo development of pig oocytes matured in vitro. Cumulus-oocyte complexes (COCs) aspirated from 2- to 6-mm follicles were matured in TCM 199 supplemented with cysteine, EGF, eCG, hCG, and PVA for 20–22h, and cultured in the same medium without hormone for an additional 20–22h. Oviducts attached to ovaries without CL were used to obtain epithelial cells. After removal of the fimbria and utero-tubal junction, oviducts were flushed with MEM supplemented with 10% FBS, and POEC clumps were cultured in the same medium for 48h. After the completion of maturation, COCs were randomly divided into four groups;; cumulus-denuded (D), cumulus-denuded with POEC (DP), cumulus-enclosed (E), and cumulus-enclosed with POEC (EP). Eight to 10 POEC clumps were co-cultured with sperm and oocytes in a 100-μL fertilization drop. Oocytes were fertilized with frozen-thawed spermatozoa for 6h in modified Tris-buffered medium containing caffeine and BSA. Presumptive zygotes were cultured in NCSU23. Oocytes were fixed and stained for the evaluation of penetration at 12h after IVF (n=549 oocytes), and cleavage rate and blastocyst formation were evaluated at 48 and 144h after IVF (n=1531 oocytes), respectively. Results were analyzed by Duncan’s multiple range test using GLM procedure in SAS. Although the sperm penetration rate in group E was lowest among all groups (P<0.05), the monospermic fertilization rate was not significantly different among treatment groups (68.6–81.9%). Although the cleavage rate and percentage blastocyst in group E were significantly lower than other groups (38.1 v. 53.6, 52.0 and 44.6%, and 15.0 v. 21.2, 23.4 and 18.5% in group D, DP, and EP, respectively), blastocyst cell number was not significantly different among treatment groups (24.9–27.3) These results suggested that the presence of cumulus cells alone during fertilization interferes with sperm penetration, cleavage, and blastocyst formation and that POEC may improve both cleavage and blastocyst formation rate.