IN-VITRO MATURATION, FERTILIZATION AND CULTURE OF BOVINE OOCYTES IN A MODIFIED MENEZO B2 MEDIUM

In this study we investigated the influence of essential amino acid composition of the medium on in vitro maturation and culture of bovine oocytes (cleavage of oocytes and development capacity of embryos). Oocytes were matured and cultured in vitro in a modified Menezo B2 medium (MMM). The medium was modified by adding amino acids, not as single compounds, but as amino acid supplements for MEM (Minimum Essential Medium) or BME (Basal Medium Eagle) tissue culture medium, which differ completely in their content of essential amino acids. In the medium with MEM supplements the content of all essential amino acids except glutamine is at least twice as high as in the BME-supplemented medium. Oocytes were randomly allocated to one of four treatments: (1) in vitro maturation (IVM) and in vitro culture (IVC) in MMM with MEM amino acids (MEM medium); (2) IVM in MEM medium, IVC in MMM with BME supplements (BME medium); (3) IVM in BME medium, IVC in MEM medium; (4) IVM and IVC in BME medium. After IVM in MEM medium, more cumulus-oocyte complexes displayed marked expansion of the cumulus cells and cleavage occurred more frequently than after IVM in BME medium. More oocytes underwent cleavage when cultured in MEM medium than in BME medium. A higher number of embryos entered the compact morula or blastocyst stage when cultured in BME medium. Development to the blastocyst stage occurred faster after IVM and IVC in BME medium than in the other groups. The results demonstrate that the content of essential amino acids of the maturation and culture medium affects the development of bovine embryos in vitro.