Correlation between first polar body morphology and further embryo development

Abstract

First polar body (PB) morphology of human oocytes can indicate further embryo development and viability. However, controversial data have been published in this topic. Our retrospective study analyses the fertilization and further development of oocytes in relation to different morphological features of the first PB. The morphology of 3387 MII oocytes from 522 in vitro fertilization (IVF) treatments were assessed before intracytoplasmic sperm injection (ICSI). Oocytes were classified according to their first PB morphology. Assessment of fertilization and embryonic development (cell number, embryo grade, amount of anuclear fragmentation and presence of multinucleated blastomeres) was performed 16-20 and 42-48 hours after ICSI. Our results show that fertilization rate and embryo quality is influenced by PB morphology, while speed of development is not affected by the morphology of the first PB. Contrary to previous findings, our results suggest that oocytes with a fragmented PB had a higher developmental ability than those with an intact PB. However, we observed a lower viability of oocytes with a large PB. Since there are contradictions in this and previous observations, an extensive study is needed with standard hormonal stimulation protocol and oocyte evaluation criteria.

Relationship between first polar body morphology before intracytoplasmic sperm injection and fertilization rate, cleavage rate, and embryo quality

“…We detected lower rates of fertilization, cleavage, and formation of good quality embryos resulting from oocytes with an enlarged first PB compared with oocytes with an intact first PB of normal size or a fragmented first PB. Our results agree with those reported by others [21,22], suggesting that oocytes with these morphological characteristics should not be used for ICSI procedures. We believe that the presence of an enlarged first PB may be associated with disproportional segregation of the mitochondria and proteins needed for the occurrence of normal fertilization and embryo development preimplantation, a possibility that requires further elucidation.…”

Predictive value of oocyte morphology in human IVF: a systematic review of the literature

“…(2008b)F, CL, CM, BL−−−−Yes*−−−−−*Ovoid: delaysEsfandiari et al . (2006)F, ED, CP−No*−−−No**−−−*Thick zona; **‘brown eggs’Fancsovits et al . (2006)F, EQ−−− Yes* −−−−−−*Fragmented better large impairedFang et al .…”

Oocyte retrieval and selection

“…Navarro et al (150) have found correlation between large PB1 and decreased fertilization, cleavage rates as well as compromised embryo quality. Surprisingly, fragmentation or degeneration of PB1 was found to be related with higher fertilization rates and lower level of fragmentation of embryos by Fancsovits et al (151), while large PB1s were associated with compromised fertilization and low embryo quality. Nevertheless, other studies have failed to demonstrate a relationship between IPB fragmentation and embryo development (25,137,142,39,152).…”