author(s)
Raghvendra Kumar and Abhishek Thakur

abstract
Reproductive efficiency of oocyte plays pivotal role in female productivity. Oocyte quality and maturation level designate its developmental competence. Brilliant Cresyl blue (BCB) staining to immature oocytes is randomly used to select competent oocyte for in vitro embryo production (IVEP). BCB staining is based on the differential activity of glucose 6- phosphate dehydrogenase (G6PDH) in immature oocytes. BCB staining sorts these oocytes into growing (BCB-) and grown (BCB+), respectively. Since, after staining with BCB, oocytes remain in a condition to be used further, this method is employed seeking for optimal results in in vitro production, and also it is simple, quick and feasible protocol. However, it is a matter of debate that prolonged morphological oocyte selections with BCB staining have any detrimental effects or not. Although, optimal results have been reported while using BCB staining, contrary reports are also available. The aim of this review is to summarise the properties associated with BCB+ oocyte and BCB- oocyte in a comparative way. Here we have also discussed evidenced pros and cons while using BCB staining.