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

In this study we investigated the influence of essential amino acid co mposition of the medium on in vitro maturation and culture of bovine o ocytes (cleavage of oocytes and development capacity of embryos). Oocy tes were matured and cultured in vitro in a modified Menezo B2 medium (MMM). The medium was modified by adding amino acids, not as single co mpounds, but as amino acid supplements for MEM (Minimum Essential Medi um) or BME (Basal Medium Eagle) tissue culture medium, which differ co mpletely in their content of essential amino acids. In the medium with MEM supplements the content of all essential amino acids except gluta mine is at least twice as high as in the BME-supplemented medium. Oocy tes were randomly allocated to one of four treatments: (1) in vitro ma turation (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 numb er of embryos entered the compact morula or blastocyst stage when cult ured in BME medium. Development to the blastocyst stage occurred faste r after IVM and IVC in BME medium than in the other groups. The result s demonstrate that the content of essential amino acids of the maturat ion and culture medium affects the development of bovine embryos in vi tro.