The Effect of Macromolecule Source and Type of Media During in vitro Maturation of Sheep Oocytes on Subsequent Embryo Development.

Background: Oocyte maturation and subsequent in vitro production (IVP) of embryos are affected by diverse groups of chemicals in maturation medium which are needed for successful mammalian oocyte maturation during which the dramatic cytoplasmic and nuclear reprogramming events take place. This study was designed to evaluate the effects of protein source (fetal bovine serum, FBS, and bovine serum albumin, BSA) as well as two different maturation media during in vitro maturation of ovine oocytes on subsequent embryo development.

Methods: Cumulus oocyte complexes were recovered from ovaries obtained from slaughter house and cultured for 24 hr in either TCM-199 or SOFaa maturation medium supplemented with 10% (v/v) FBS or 0.8% (w/v) BSA. Data were analyzed by one-way ANOVA using Sigma Stat (Ver. 2). A p-value smaller than 0.05 was considered statistically significant.

Results: The proportions of cleavage and total blastocyst (evaluated on days 3 and 6, respectively) were significantly higher in FBS than BSA supplemented groups, though no differences were observed between the two used different maturation media. The cryotolerance of blastocysts was negatively influenced by the presence of FBS rather than BSA during IVM. The quality of produced embryos, however, was affected neither by the source of macromolecules nor the maturation medium in terms of hatching rate, total blastocyst cells and inner cell mass/total cell ratio.

Conclusion: The rate of oocyte development was improved by the presence of FBS, though the cryosurvival of resulting blastocysts was negatively influenced by the presence of the serum during in vitro production of sheep oocytes.