Fig. 2
From: Oxidative stress in sperm affects the epigenetic reprogramming in early embryonic development
The developmental capacity of embryos is drastically reduced upon oxidative stress in sperm. a Fertilization rates of sperm treated without (control) or with H2O2 (+H2O2) were evaluated 20 h after IVF by staining the pronuclei with DAPI. Images were acquired with an inverted Leica CTR6000 microscope (software: Leica Microsystems LAS-AF6000; Leica Microsystems, Bensheim, Germany). The fertilization capacity (%) was quantified by calculating the number of obtained zygotes versus the total number of oocytes used in each IVF experiment. Each data point represents the mean of one of four independent experiments. Total amount of oocytes: 225 (control) and 209 (+H2O2). b Cleavage rate (%) was quantified by calculating the number of cleaved embryos (two-cell stage and further) obtained 24 h after IVF versus the total number of oocytes used in each IVF experiment. Each data point represents the mean of one of the four independent experiments. Total amount of oocytes: 100 (control), 123 (+H2O2). Arrows indicate the cleaved embryo stages. c Blastocyst rate (%) was quantified by calculating the number of blastocysts obtained 8 days after IVF versus the number of embryos that reached the cleavage stage 24 h after IVF. Each data point represents the mean of one of the four independent experiments. Total amount of oocytes: 148 (control) and 165 (+H2O2). Arrows indicate the blastocyst stage embryos. d Arrested embryos were evaluated 36 h after IVF. Quantifications were assessed by counting the number of embryos that were arrested at two- to four-cell stages 36 h after IVF versus the number of embryos that already reached two- to four-cell stage 24 h after IVF. Each data point represents the mean of one of three independent experiments. Total amount of oocytes: 127 (control) and 141 (+H2O2). Statistical analyses were performed using Student’s t-test (two-tailed). Error bars indicate s.d. ns: non-significant and refers to P = 0.091; *P < 0.05; **P < 0.01; ***P < 0.0001. Maternal pronucleus: mPN/♀/continuous line; paternal pronucleus: pPN/♂/dashed line. Scale bars, 50 μm