Polanski Z
Department of Genetics and Evolution, Jagiellonian University, Kraków, Poland.
Int J Dev Biol. 1995 Dec;39(6):1015-20.
Some mammalian oocytes fail to complete maturation in vitro and arrest development at the first metaphase stage. The response of such blocked oocytes to sperm penetration was investigated. Ovarian mouse oocytes from two inbred strains, CBA/Kw and KE, were cultured in vitro for 20 h. Both oocytes arrested at the first metaphase (MI oocytes) and second metaphase (MII oocytes) were then inseminated. The majority of MII and MI oocytes reinitiated meiosis in response to sperm penetration, although those from the CBA strain did with higher frequency. Moreover, a high proportion of unpenetrated oocytes from CBA, but not the KE strain, resumed meiosis (33% for MII and 48% for MI oocytes, respectively). Parthenogenetic activation of MI-arrested oocytes was demonstrated in (CBAxKE)F1 mice; ovarian oocytes matured in vitro and then treated by electric shock were activated with a similar total frequency of 52.4% for MI and 47.8% for MII oocytes. The rate of activation increased equivalently for both MI and MII oocytes as the length of maturation prolonged. This demonstrates that mouse oocytes arrested at MI during their maturation in vitro continue cytoplasmic maturation and become capable of undergoing activation in a way similar to those maturing to MII. Additionally, in MII oocytes cultured for an equal time in vitro the rate of activation increased with the time lapse after first polar body (PB1) extrusion. This indicates that after PB1 extrusion, the oocyte requires some resting time before it may be activated, perhaps to restore the proper balance between elements of the cell cycle controlling the mechanism involved in first meiotic division.
一些哺乳动物的卵母细胞在体外无法完成成熟，并在第一次中期阶段停止发育。研究了这类阻滞卵母细胞对精子穿透的反应。将来自两个近交系CBA/Kw和KE的小鼠卵巢卵母细胞进行体外培养20小时。然后对停滞在第一次中期（MI卵母细胞）和第二次中期（MII卵母细胞）的卵母细胞进行授精。尽管来自CBA品系的卵母细胞对精子穿透反应重新启动减数分裂的频率更高，但大多数MII和MI卵母细胞都能对精子穿透做出反应而重新启动减数分裂。此外，CBA品系未被穿透的卵母细胞中有很大比例（MII卵母细胞为33%，MI卵母细胞为48%）恢复了减数分裂，而KE品系则不然。在（CBA×KE）F1小鼠中证实了MI期阻滞卵母细胞的孤雌激活；体外成熟然后接受电击处理的卵巢卵母细胞被激活，MI卵母细胞和MII卵母细胞的总激活频率相似，分别为52.4%和47.8%。随着成熟时间的延长，MI和MII卵母细胞的激活率均同等增加。这表明在体外成熟过程中停滞在MI期的小鼠卵母细胞继续进行细胞质成熟，并能够以类似于成熟到MII期的卵母细胞的方式进行激活。此外，在体外培养相同时间的MII卵母细胞中，激活率随着第一极体（PB1）排出后的时间推移而增加。这表明在PB1排出后，卵母细胞在被激活之前需要一些静止时间，这可能是为了恢复控制第一次减数分裂相关机制的细胞周期元件之间的适当平衡。
