Vitrification of immature bovine cumulus-oocyte complexes: effects of cryoprotectants, the vitrification procedure and warming time on cleavage and embryo development

未成熟牛卵丘-卵母细胞复合体的玻璃化冷冻：冷冻保护剂、玻璃化冷冻程序和复温时间对卵裂和胚胎发育的影响