ASSESSMENTS OF COMPETENCE IN BOVINE OOCYTE

Abstract

Although substantial progress has been made in the in vitro production systems, little increase in the blastocyst rates has been achieved. The percentage of embryos that are able to have normal development is still lower in oocytes matured in vitro than in those matured in vivo. Several factors affect the success of maturation, however the oocyte competence is one of the most important. Only competent oocytes are capable of being fertilized and have a normal embryonic development. Therefore, the identification of competent oocytes is essential to improve the performance of assisted reproduction techniques (ARTs), as well as to conduct studies involving such theme. Several parameters can be used as indicative of competence such as morphology, size of the follicle, staining with brilliant cresyl blue (BCB), first cleavage and donor´s age. More recently these parameters have been used for studies of gene expression associated with competence. Several candidate genes have been identified, however, the mechanisms involved in its acquisition are still not well known. These studies are critical in order to identify these mechanisms, which then would allow to define more efficient systems to increase the availability of competent oocytes and ultimately, to optimize the use of ARTs.