Sundström P, Nilsson B O
Department of Obstetrics and Gynaecology, Allmänna Sjukhuset, Malmö, Sweden.
Hum Reprod. 1988 Jul;3(5):613-9. doi: 10.1093/oxfordjournals.humrep.a136756.
Oocytes collected in stimulated cycles are more readily fertilized after preincubation than are oocytes inseminated immediately after collection. It has not been ascertained, however, whether this increase in the fertilization rate is due to extrusion of the first polar body (meiotic maturation) during this period, or to some conclusive cytoplasmic maturation subsequent to the polar body extrusion. When analysing oocytes with a polar body (n = 14) by transmission electron microscopy, differences were observed in the appearance of cytoplasmic features which were correlated to the total durations both of systemic human chorionic gonadotrophin influence before collection and of oocyte culture. These differences were manifested as a delayed formation in aggregates of the smooth endoplasmic reticulum in the ooplasm of oocytes having a polar body and might have signified a cytoplasmic maturation. The degree of asynchrony in the oocytes varied and this could explain why some oocytes can be fertilized when inseminated shortly after collection and others not until 8 h or even more after collection. Thus, although meiotic and cytoplasmic maturation is likely to be synchronized at ovulation of an oocyte in a natural cycle, they appear to be mainly asynchronous in oocytes collected in stimulated cycles.
在刺激周期中收集的卵母细胞，与收集后立即授精的卵母细胞相比，预孵育后更容易受精。然而，尚未确定受精率的这种提高是由于在此期间第一极体的排出（减数分裂成熟），还是由于极体排出后某种决定性的细胞质成熟。当通过透射电子显微镜分析有极体的卵母细胞（n = 14）时，观察到细胞质特征的外观存在差异，这些差异与收集前全身人绒毛膜促性腺激素影响的总持续时间以及卵母细胞培养的总持续时间相关。这些差异表现为有极体的卵母细胞卵质中滑面内质网聚集体形成延迟，这可能意味着细胞质成熟。卵母细胞中的不同步程度各不相同，这可以解释为什么有些卵母细胞在收集后不久授精就能受精，而另一些则要在收集后8小时甚至更长时间才能受精。因此，尽管在自然周期中卵母细胞排卵时减数分裂和细胞质成熟可能是同步的，但在刺激周期中收集的卵母细胞中它们似乎主要是不同步的。
