T HE SUCCESS of in vitro embryo production is ultimately dependent on the number and
quality of cumulus-oocyte complexes harvested from ovaries. The morphological criteria
are routinely used for oocytes selection in most laboratories. There is brilliant cresyl blue stain
(BCB) test allowing the selection of developmentally competent oocytes which is a simple,
quick, economic and feasible protocol. BCB is known to be a non-invasive methodology that allows the selection of immature oocytes in several species. BCB test determine the intra cellular
activity of glucose-6-phosphate dehydrogenase (G6PDH) that gradually decreases its activity
as oocytes reach their growth phase. The using of BCB test before IVM is still controversial, so
this review describes the use of BCB staining test for oocytes and embryo selection to investigate
the impact of application of this stain in in-vitro maturation and embryo production in animals.