Impact of bovine oocyte maturation media on oocyte transcript levels, blastocyst development, cell number, and apoptosis

The objectives were 1) to investigate the effects of oocyte maturation in s erum-free and amino acid-supplemented defined media on oocyte transcript le vels, blastocyst cell number, and apoptosis; 2) to investigate the influenc e of oocyte maturation culture atmosphere on blastocyst development, total cell number, and apoptosis; and 3) to examine the influence of epidermal gr owth factor (EGF) during oocyte maturation on blastocyst cell number and ap optosis. The results demonstrate that blastocysts derived from in vitro mat uration, fertilization, and embryo culture protocols undergo apoptosis but that apoptotic levels are not greatly influenced by the oocyte maturation e nvironment. Amino acid supplementation of oocyte maturation media was assoc iated with enhanced developmental frequencies, increased blastocyst cell nu mber, and elevated oocyte maternal mRNA levels. Oocyte maturation with supp lemented synthetic oviduct rFluid medium (cSOFMaa) resulted in blastocyst c ell numbers comparable to those observed with Tissue Culture Medium 199 + n ewborn calf serum. Blastocyst development was reduced following oocyte matu ration under a 5% CO2, 7% O-2, 88% N-2 culture atmosphere. EGF supplementat ion of oocyte maturation medium resulted in a concentration-dependent incre ase in blastocyst development but did not influence blastocyst total cell n umber or apoptosis. Our findings indicate that cSOFMaa medium is an effecti ve base medium for bovine oocyte maturation.