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Table 2 Effect of maternal obesity and vitrification on embryo development on days 2–5 of culture

From: Obesity does not aggravate vitrification injury in mouse embryos: a prospective study

  Fresh Vitrified P a
Normal weight Obese Normal weight Obese
No. of zygotes 30.9 ± 1.9 30.3 ± 1.3 - - NS
Cleavage rate (%) 64.3 ± 5.2 61.2 ± 4.5 - - NS
Six–eight-cell ratio (%) 75.1 ± 5.3 62.4 ± 4.2 - - <0.05
Morula (%)      
Day 4 19.5b 41.6c 34.2 42.2 <0.01
Day 5 5.7 9.1 10.6 10.8 NS
≥Early blastocyst (%)      
Day 4 40.2 32.5 36.8 38.5 NS
Day 5 39.1 49.4 42.1 39.8 NS
≥Expanded blastocyst (%)      
Day 4 35.7b 18.1c 25.0 16.9 <0.01
Day 5 48.3b 24.6c 36.8 32.5 <0.01
Degeneration rate (%)      
Day 4 4.6 7.8 3.9 2.4 NS
Day 5 6.9b 16.9c 10.5 16.9 <0.01
  1. Notes: Data represent n = 10 mice/group (from 630 and 609 total zygotes in normal-weight and obese females, respectively). Cleavage rate = number of cleaved embryos on day 2/total number of one-cell embryos recovered. Six–eight-cell ratio = mean number of embryos scored morphologically as having six–eight cells/mean number of cleaved embryos on day 2. Day 4 and 5 data are expressed as mean number of embryos at each stage/mean number of six–eight-cell embryos on day 3 (fresh) or total number of thawed embryos (vitrified). Degeneration rate = number of embryos that have ceased development/number of six–eight-cell embryos on day 3 (fresh) or number of thawed embryos (vitrified). ≥Early blastocyst = early-, mid-, or late-stage blastocyst. ≥Expanded blastocyst = expanded, hatching, or hatched blastocyst. NS = not significant; aChi-squared test; bvs.c, P<0.01.