Rosenbusch Bernd
Department of Gynaecology and Obstetrics, University of Ulm, Prittwitzstraße 43, 89075 Ulm, Germany.
Int J Reprod Med. 2014;2014:418198. doi: 10.1155/2014/418198. Epub 2014 May 6.
The assessment of oocytes showing only one pronucleus during assisted reproduction is associated with uncertainty. A compilation of data on the genetic constitution of different developmental stages shows that affected oocytes are able to develop into haploid, diploid, and mosaic embryos with more or less complex chromosomal compositions. In the majority of cases (~80%), haploidy appears to be caused by gynogenesis, whereas parthenogenesis or androgenesis is less common. Most of the diploid embryos result from a fertilization event involving asynchronous formation of the two pronuclei or pronuclear fusion at a very early stage. Uniparental diploidy may sometimes occur if one pronucleus fails to develop and the other pronucleus already contains a diploid genome or alternatively a haploid genome undergoes endoreduplication. In general, the chance of obtaining a biparental diploid embryo appears higher after conventional in vitro fertilization than after intracytoplasmic sperm injection. If a transfer of embryos obtained from monopronuclear oocytes is envisaged, it should be tried to culture them up to the blastocyst since most haploid embryos are not able to reach this stage. Comprehensive counselling of patients on potential risks is advisable before transfer and a preimplantation genetic diagnosis could be offered if available.
在辅助生殖过程中，对仅显示一个原核的卵母细胞进行评估存在不确定性。不同发育阶段遗传构成数据的汇总表明，受影响的卵母细胞能够发育成具有或多或少复杂染色体组成的单倍体、二倍体和嵌合胚胎。在大多数情况下（约80%），单倍体似乎是由雌核发育引起的，而孤雌生殖或雄核发育则不太常见。大多数二倍体胚胎是由涉及两个原核异步形成或在非常早期阶段原核融合的受精事件产生的。如果一个原核未能发育而另一个原核已经包含二倍体基因组，或者单倍体基因组进行了核内复制，有时可能会出现单亲二倍体。一般来说，与卵胞浆内单精子注射相比，传统体外受精后获得双亲二倍体胚胎的机会似乎更高。如果设想移植从单原核卵母细胞获得的胚胎，应尽量将它们培养至囊胚期，因为大多数单倍体胚胎无法达到这一阶段。在移植前，建议对患者进行关于潜在风险的全面咨询，如有条件，可提供植入前基因诊断。
