The Potential Impacts of Selecting Viable Oocytes on Further Embryonic Development in Mammals: A Review

Selecting viable fully grown germinal and matured oocytes were positively effect on further embryonic development and live birth. The use of feed and hormonal supplementation and biotechnologies to enhance oocyte competence was evaluated. In addition, the oocytes were selected based on ovarian follicular stage, follicles and oocytes morphology, follicular fluid characters and gene expression. Changes were obtained in oocyte maturation, fertilization and further embryo cleavage and development over selecting viable oocytes. The larger follicle diameter, the translucent follicle and the higher blood supply the higher developmental competence of resulting oocytes. The higher surrounding cumulus cells and homogeneity of cytoplasm the higher developmental competence of oocytes. In addition, oocytes obtained during luteal stage compared to those obtained during follicular phase were highly or comparably developed to embryos. Furthermore, follicular fluid characters and gene expression might predict the embryonic developmental competence of oocytes in addition to their viable staining with brilliant cresyl blue. In conclusion, the characters of ovarian follicles, oocytes, follicular fluid and gene expression have significant implications on further oocyte developmental competence in different mammalian species.