In vitro fertilization of porcine oocytes in chemically defined medium

Abstract

Abstract Porcine follicular oocytes matured in vitro were inseminated with ejaculated boar spermatozoa. We examined whether or not protein is essential for spermatozoa to penetrate oocytes when added during preincubation of spermatozoa, during sperm-oocyte coincubation, or during both periods. The absence of additional protein (bovine serum albumin; BSA) in preincubation media had no effect on the sperm penetration of oocytes, although fetilization media with protein showed higher rates of penetrated oocytes than media without additional protein (77% with BSA and 57% with fetal bovine serum; FBS, vs 14% with no macromolecule, 19% with polyvinylalcohol; PVA, and 27% with polyvinylpyrrolidone; PVP). A high concentration of spermatozoa at insemination increased the rate of sperm penetration even in medium without additional protein. Oocytes with or without cumulus cells were inseminated with preincubated spermatozoa in the fertilization medium without additional protein. The results showed no difference in the penetration rate between oocytes with and those without cumulus cells. In conclusion, although BSa in the fertilization medium was found to accelerate the ability of porcine spermatozoa to penetrate porcine oocytes matured in vitro, protein and cumulus cells were not essential for in vitro penetration of oocytes.