Intracytoplasmic sperm injection: correlation of oocyte grade based on polar body, perivitelline space and cytoplasmic inclusions with fertilization rate and embryo quality

Abstract

The extent to which the morphology of the oocyte at the light microscopy level is related to the results of intracytoplasmic sperm injection (ICSI) is controversial. In this study, after cumulus removal, oocytes were graded into four groups according to the status of the first polar body, size of the perivitelline space and the presence of cytoplasmic inclusions. Oocyte data from 65 consecutive patients were reviewed. The results showed that, for oocytes without cytoplasmic inclusions, the fertilization rate and embryo development beyond 2-cell stage were significantly lower (P < 0.01) in the oocytes at grade 1-2 (poor) than those in oocytes at grade 3-4 (good). Grade 4 oocytes without inclusions gave the highest proportion (66.7%) of good embryos with grading 1-2 (grade 1 best; P < 0.01). A higher proportion of grade 1-2 oocytes (44.7%; P < 0.05) was obtained from patients older than 35 years. More oocytes containing cytoplasmic inclusions were seen in patients diagnosed as having female factor infertility (24.9%; P < 0.01) and older than 35 years (26.5%; P < 0.05) compared to patients with male factor infertility and younger than 35 years. The fertilization rate and embryo development were not associated with the oestradiol concentration on the day of human chorionic gonadotrophin administration or the total number of oocytes retrieved. The results suggest that human oocyte grading based on the triple factors first polar body, size of perivitelline space and cytoplasmic inclusions is related significantly to fertilization rate and embryo quality after ICSI.

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

“…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.…”

“…Part of these studies [4,6,7,10,13] was performed in a retrospective manner. 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].…”

“…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].…”

Diploid, but not haploid, human embryonic stem cells can be derived from microsurgically repaired tripronuclear human zygotes

“…The method of assessing the quality of embryos at the eight-cell stage was modified from the criteria published by Xia. 52 The scores were as follows: for 8G1 scoring, the embryos must have eight blastomeres with equal volume and with fragments that are less than 5%; for 8G2 scoring, the embryos must have eight blastomeres with equal volume and with fragments that are less than 20%; for 8G3 scoring, the embryos must have 4-8 blastomeres with unequal volume and with fragments less than 50%; and for 8G4 scoring, the embryos must have almost no blastomeres and consist nearly entirely of fragments. The method of assessing the quality of embryos at the blastocyst stage was referenced in Dokras's study.…”