Female adiposity might impair oocyte number and maturity in conventional IVF but not in mini-IVF. These data suggest that mild ovarian stimulation might yield healthier oocytes in obese women.

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In mammals, the dynamic reprogramming of DNA methylation begins during gametogenesis and continues through embryogenesis. Recently, immunofluorescence staining with an antibody against 5-methylcytosine (anti-5-MeC) has revealed active demethylation of the male pronucleus in zygotes beginning at 4-6 h after fertilization. In this study, we characterized the DNA methylation patterns in mouse zygotes and in human tripronucleate (3 PN) zygotes discarded after conventional fertilization or following ICSI. Pronuclei were subjected to fluorescence in-situ hybridization to identify the X and/or Y chromosomes and then stained with anti-5-MeC. In diandric 3 PN zygotes from conventional IVF, we consistently observed one strongly and two weakly stained pronuclei. In contrast, the majority of 3 PN ICSI zygotes, mainly digynic zygotes, displayed two strongly and one weakly stained pronuclei. Two zygotes from ICSI failed to show any staining difference among the three pronuclei. Our results indicate that the active demethylation of male pronuclei occurs in both mouse and human zygotes. It is possible that the abnormal methylation patterns resulting from a dysfunctional cytoplasm may occur in a small number of oocytes and may affect embryonic viability.

The change of elastic moduli of dry sandstone with effective pressure is a result of the subsequent closing of a series of pores. This process is approximated with the KT model and the expression of effective pressure dependence of pore aspect ratio spectra. By inverse modelling, the pore aspect ratio spectra of the water-saturated sandstone samples are obtained from velocity measurements. These pore aspect ratio spectra are then used to calculate the elastic moduli of the corresponding dry sandstone samples. An exponential function is found to best fit the rate of change of the dry elastic moduli with effective pressure.

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