Fig. 1

Viability evaluation in oocytes and cumulus cells. Representative images from oocytes (a, b) and cumulus cells (c, d) for viability evaluation in different groups at 40×. Oocyte (n = 304) and cumulus cells (n = 400) viability was evaluated after 44 h of in vitro maturation. For oocytes and cumulus cells, different staining agents were used: methyl-thiazolyl-tetrazolium (MTT) and trypan blue, respectively. a Stained purple oocyte: alive; b unstained oocyte: dead; c unstained cumulus cells: alive; d stained cumulus cells: dead. Scale bar: 30 μm. n = number of evaluated cells