Edashige Keisuke
College of Agriculture Kochi University Nankoku Kochi Japan.
Reprod Med Biol. 2016 Dec 5;16(1):36-39. doi: 10.1002/rmb2.12007. eCollection 2017 Jan.
The permeability of the plasma membrane to water and cryoprotectants is one of the important factors for determining the suitable condition for the vitrification of mammalian oocytes and embryos. Water and cryoprotectants move slowly through oocytes and early embryos, principally by simple diffusion, in the mouse, bovine, pig, and human. In contrast, water, glycerol, and ethylene glycerol move rapidly through morulae and blastocysts, principally by facilitated diffusion via aquaporin 3, in the mouse and bovine; whereas, in the pig, the permeability to water and these cryoprotectants increases not at the morula stage but at the blastocyst stage and further increases at the expanded blastocyst stage. Dimethyl sulfoxide also moves rapidly via channels other than aquaporin 3 in the mouse. In contrast, propylene glycol moves through morulae and blastocysts principally by simple diffusion in the mouse, bovine, and pig, as through oocytes. Therefore, the permeability of mammalian oocytes and embryos at early stages to water and cryoprotectants is low, but that of embryos at later stages to water and some cryoprotectants is markedly high by channel processes, although species specificity exists in some cases.
质膜对水和冷冻保护剂的通透性是决定哺乳动物卵母细胞和胚胎玻璃化合适条件的重要因素之一。在小鼠、牛、猪和人类中，水和冷冻保护剂主要通过简单扩散缓慢穿过卵母细胞和早期胚胎。相比之下，在小鼠和牛中，水、甘油和乙二醇主要通过水通道蛋白3介导的易化扩散快速穿过桑椹胚和囊胚；而在猪中，对水和这些冷冻保护剂的通透性不是在桑椹胚阶段增加，而是在囊胚阶段增加，并在扩张囊胚阶段进一步增加。在小鼠中，二甲基亚砜也通过水通道蛋白3以外的通道快速移动。相比之下，在小鼠、牛和猪中，丙二醇主要通过简单扩散穿过桑椹胚和囊胚，就像穿过卵母细胞一样。因此，哺乳动物早期卵母细胞和胚胎对水和冷冻保护剂的通透性较低，但后期胚胎对水和一些冷冻保护剂的通透性通过通道过程明显较高，尽管在某些情况下存在物种特异性。
