Vitamin C Improves Oocyte In Vitro Maturation and Potentially Changes Embryo Quality in Cattle.

To obtain high-quality bovine oocytes, the effects of vitamin C (VC) on the IVM of bovine oocytes and early embryo development were investigated. The results showed the following. (1) The IVM medium containing 50 µg/mL VC improved the oocyte maturation rate but did not affect the parthenogenetic embryo development. (2) The IVC medium containing 20 µg/mL VC improved the cleavage rate of the IVF embryos and enhanced the mRNA transcriptions of pluripotency gene Oct4 , Sox2 , Cdx2, and Nanog in the blastocysts but had no effects on the blastocyst rate. (3) Combining supplementation of 50 µg/mL VC in IVM medium + 20 µg/mL VC in IVC medium (named as VC 50/20, similar hereinafter) elevated the cleavage rate of IVF embryos and enhanced the mRNA expressions of Oct4 , Sox2 , Cdx2, and Nanog in the blastocysts. (4) Combination of VC 0/20 and VC 50/20 enhanced the transcription of anti-apoptotic gene Bcl-2 and VC 50/0 weakened the transcription of pro-apoptotic gene Bax , while VC 0/40 and VC 0/60 increased Bax expression and diminished the Bcl-2 / Bax ratio in blastocysts. Together, employing 50 µg/mL VC improves the IVM of bovine oocytes and combination of VC 50/20 potentially changes bovine embryo quality by enhancing the expressions of the pluripotency genes and regulating the expressions of apoptosis-related genes.