Polar body morphology and spindle imaging as predictors of oocyte quality

Abstract

It has been suggested that first polar body (PBI) morphology reflects oocyte competence. Oocytes with an intact normal-sized PBI have been described as generating better day 2 embryos, higher blastocyst yield, and increased pregnancy and implantation rates. In other studies, PBI morphology was found to be unrelated to fertilization rate, embryo quality, and blastocyst formation. In a prospective analysis, the predictive value of the PBI was investigated by comparing the development of oocytes retrieved from intracytoplasmic sperm injection patients and displaying different PBI morphology, classified according to the following characteristics: normal size and smooth surface (I), fragmented (II), rough surface (III), or large size (IV). Fertilization rates were 59, 57, 64 and 60% respectively. No significant differences were found between the various groups. The proportions of high quality (grade A) day 2 embryos were also comparable among groups I-III (14, 12 and 17% respectively), while the low number of grade A embryos in group IV (two embryos) did not allow comparison with the other classes. These data do not suggest that PBI selection can contribute to identification of embryos with high developmental ability. In order to establish alternative criteria for oocyte selection, a metaphase II (MII) spindle analysis was also conducted via Polscope. In oocytes of patients of different age, spindle retardance (which reflects the high order and density of microtubules) was compared with parameters of embryo development. In aged patients, a trend was observed between low retardance and poor embryo quality, although in general the association between retardance and oocyte developmental performance did not reach statistical significance.

Does first polar body morphology predict oocyte performance during ICSI treatment?

“…Only few published reports have examined the association between 1 PB morphology, implantation rate [5,6,8,11,13] and pregnancy rate [5,12,13]. Our results are in accordance with some of the previously published reports [5,6] however, they contradict other reports [8][9][10][11]13]. Several explanations could be suggested to clarify this discrepancy.…”

“…Moreover, there is a large discrepancy in the literature concerning the timing of 1 PB morphology evaluation ranging from 2 to 11 h following retrieval [4][5][6][7][8][9][10][11][12][13]. As has already has been explained this might have a crucial effect on 1 PB morphology.…”

“…In addition, few of these studies included only "good quality" infertile women [11,13] while others defined poor responders as those having below 10 oocytes per retrieval [8]. As well, few studies estimated only a selected number of oocytes from each retrieved infertile woman [9,13]. Other oocytes were discarded or cryopreserved.…”

“…Part of these studies has shown a correlation between the 1 PB morphology and oocyte performance during ICSI treatment [4][5][6]12] while others did not [8,9,11,13]. Moreover, the grounds for this discrepancy between the studies are still not clear.…”

“…Several investigators have questioned whether normal development of the 1 PB morphology is correlated to fertilization rate [4][5][6][7][8][9][10][11], cleavage rate [4,7,10], embryo quality [4][5][6][7][8][9][10][11][12][13], blastocyst formation [8,12] as well as implantation [5,8,[10][11][12][13] and pregnancy rates [5,6,10,13].…”