In vitro embryo production of Bos taurus oocytes treated with brilliant cresyl blue ( BCB ) from small and large follicles

Oocyte quality is important for in vitro embryo production success. Morphological features such as follicular size, oocyte diameter, cytoplasm appearance, and zona pellucida integrity determine oocyte’s developmental competence. Evaluations at the meiotic stage, and of metabolic state and viability have also been performed. Therefore, the aim of this study was to elucidate if Bos taurus oocytes from follicles of different sizes, identified by the brilliant cresyl blue staining (BCB), show improved in vitro embryo development. Oocytes from small (2.0– 4.9 mm) and large (5.0–10.0 mm) follicles were classified according to their cytoplasm appearance, blue (BCB+) and colorless (BCB−), and by measuring their diameters. The analyzed parameters were viability before maturation and after fertilization, assessment of the meiotic stage, embryo development and blastocyst formation, and the results for BCB+ and BCB− oocytes from small and large follicles were compared. The results varied according to the oocyte classification, oocyte from small follicles showed an increase in blastocyst production. We conclude that BCB staining allows the select on of oocytes from small follicles that are competent of reaching the blastocyst stage in Bos taurus.