EFFICIENCY OF EARLY EMBRYO CULTURE OF ANIMALS (review)

Abstract

Further development of the technology of obtaining and transplanting embryos directly depends on the quality of the reproductive material obtained from females. It was established that the quality of oocytes affects early embryonic survival, the establishment and maintenance of pregnancy, fetal development and even the productivity of adult animals. It has been proven that the ability of oocytes to develop is acquired gradually and increases with the development of follicles. The ability of an oocyte to develop into an embryo depends on the presence of sufficient specific information in the form of mitochondrial RNA (mRNA) or proteins. Researchers have shown that if this information is insufficient, defects in nuclear or cytoplasmic maturation or both processes may occur, which affects the development of fertilized oocytes. It has been established that oocytes obtained from larger follicles have greater developmental competence compared to smaller follicles. The competence of oocyte development largely correlates with the morphology of cumulus oocyte complexes. In addition to morphological or biochemical markers, molecular markers have also been studied. Despite extensive research, no specific markers of oocyte developmental competence have been described so far. It has been shown that oocyte pre-maturation and maturation conditions affect gene expression not only in the oocyte but also before the blastocyst stage.