Kattera Suresh, Chen Christopher
Centre for Reproductive Medicine and Gleneagles IVF Centre, Gleneagles Hospital, Singapore 258500.
Hum Reprod. 2004 Feb;19(2):294-9. doi: 10.1093/humrep/deh064.
Pronuclear zygote morphology has gained much attention recently due to its possible value in predicting implantation and pregnancy. The present study was performed to assess the developmental potential of zygotes with four different pronuclear orientations.
This prospective study involved 150 IVF and 190 ICSI patients seeking fertility treatment. Pronuclear zygotes were classified for orientation of the pronuclei in relation to the second polar body placed at the 6 o'clock position. Four types of pronuclear (PN) zygote were recognized, namely PN(1), PN(2), PN(3) and PN(4). The main outcome measures were early cleavage rate, quality of embryos, and implantation and pregnancy rates.
The most common types of pronuclei orientations were PN(1) (31.5%) and PN(2) (29.3%), followed by PN(3) (20.5%) and PN(4) (18.5%). A significantly higher proportion of zygotes with PN(1) and PN(4) types of pronuclear orientation underwent early cleavage and developed into grade I embryos compared with other types (P < 0.0001). There was a tendency for higher implantation and pregnancy rates among patients who received embryos developed from PN(1)- and PN(4)-type oocytes, but this was not statistically significant.
Zygotes exhibit four types of pronuclear orientation, and this is independent of the fertilizing spermatozoon or its entry point into the oocytes, whether IVF or ICSI is employed. Early cleavage was associated with PN(1)- and PN(4)-type zygotes, but implantation and pregnancy rates were not associated with pronuclear orientation. Implantation and pregnancy rates tended to be higher for embryos developed from PN(1) and PN(4) pronuclear zygotes. Further studies on a combination of pronuclear orientation and equality of nucleoli may provide a better guide to the implantation potential of embryos.
原核受精卵形态因其在预测着床和妊娠方面的潜在价值，近来备受关注。本研究旨在评估具有四种不同原核取向的受精卵的发育潜力。
这项前瞻性研究纳入了150名接受体外受精（IVF）和190名接受卵胞浆内单精子注射（ICSI）寻求生育治疗的患者。根据原核相对于位于6点钟位置的第二极体的取向，对原核受精卵进行分类。识别出四种类型的原核（PN）受精卵，即PN(1)、PN(2)、PN(3)和PN(4)。主要观察指标为早期卵裂率、胚胎质量以及着床率和妊娠率。
最常见的原核取向类型为PN(1)（31.5%）和PN(2)（29.3%），其次是PN(3)（20.5%）和PN(4)（18.5%）。与其他类型相比，具有PN(1)和PN(4)类型原核取向的受精卵早期卵裂并发育为I级胚胎的比例显著更高（P < 0.0001）。接受由PN(1)型和PN(4)型卵母细胞发育而来的胚胎的患者，其着床率和妊娠率有升高趋势，但差异无统计学意义。
受精卵表现出四种原核取向类型，这与受精精子或其进入卵母细胞的位点无关，无论采用IVF还是ICSI。早期卵裂与PN(1)型和PN(4)型受精卵相关，但着床率和妊娠率与原核取向无关。由PN(1)和PN(4)原核受精卵发育而来的胚胎着床率和妊娠率往往更高。对原核取向和核仁均等性相结合的进一步研究，可能会为胚胎的着床潜力提供更好的指导。
