EFFECTS OF CULTURE CONDITIONS ON PIG EMBRYO DEVELOPMENT IN VITRO
The technology of oocyte extracorporal maturation and pig embryo culture is widely claimed in the field of research of early development mechanisms as well as in works on embryo transplantation, cloning and producing of transgenic animals. However, optimal conditions for generation of these cells are not fully determined. In the present work, effects of oxygen concentrations in the gas atmosphere and of multiplicity of the culture medium replacement on the pig embryo development in vitro were investigated. For this aim, matured and artificially activated oocytes were incubated using the gas atmosphere with a high (5% СО <sub>2</sub> and 20 % О <sub>2</sub>) and low (5% СО <sub>2</sub> and 5 % О <sub>2</sub>) oxygen concentration. The embryo medium replacement was conducted once (on the third day of culture) or doubly (on the second and fourth days) in both cases. The greatest yield of blastocysts (25.4 %) was observed in the case of incubation of artificially activated oocytes in the presence of 5 % СО <sub>2</sub> and 20 % О <sub>2</sub> under the condition of double replacement of the culture medium. At the same time culture of pig partenogenic embryos in the gas atmosphere containing a lower concentration of oxygen was less efficient (21.3 % of blastocysts). The single replacement of the embryo medium exerted a negative influence on the oocyte development to the blastocyst stage. Meanwhile, the negative effect was more expressed in the group incubated in the presence of 5 % СО <sub>2</sub> and 20 % О <sub>2</sub>, in which the proportion of blastocysts decreased by 12.7 % (p < 0.001). Thus, the gas atmosphere with the high content of oxygen is more favorable for in vitro culture of pig partenogenic embryos under the condition of double replacement of the embryo medium.