超低温冷冻对奶牛胚胎超微结构的影响

奶牛冷冻胚胎移植成活率较鲜胚移植明显低.为明确低温冷冻造成胚胎损伤的机理、为冷冻保存方法的进一步改进提供理论依据,利用透射电子显微镜观察了奶牛胚胎常规冷冻和玻璃化冷冻前后的超微结构变化.结果表明,奶牛鲜胚细胞分为两种类型:一种位于内细胞团(ICM)外层,胞质电子致密度低而着色浅,并含有大量的线粒体和内质网;另一种位于ICM中心区域,着色较深,溶酶体的数量多,其余细胞较较少.常规冷冻后,透明带和卵周隙明显变宽,细胞间接触变得松散.囊胚中含有退化的胞核和凋亡小体,内质网变大、变粗,脂滴明显增多.玻璃化冷冻后,ICM细胞的结构发生破坏,部分细胞发生崩解,细胞碎片大量分布于细胞间隙和卵周隙中,并可见大量的脂滴,凋亡细胞和凋亡小体增多.冷冻过程对早期胚胎细胞器的损伤可能是移植后成活率下降的主要原因.

Effect of Cryopreservation on the Embryo Ultrastructure in Dairy Cow

The objective of present study was to investigate the influence of conventional slow freezing and vitrification on the morphology of early bovine embryos.By the transmission electron microscope,two types of cells with different electron-density of their cytoplasm in the bovine morulae were observed.One appeared light in color with low electron-density cytoplasm,and possessed numerous cellular organelles such as Mi and Er and had microvilli projecting into the perivitelline space(PvS).The other was stained m...