Effect of IVF and laser zona dissection on DNA methylation pattern of mouse zygotes

Mamm Genome. 2009 Sep-Oct;20(9-10):664-73. doi: 10.1007/s00335-009-9227-0. Epub 2009 Oct 13.

Abstract

In vitro fertilization (IVF) and zona pellucida laser microdissection-facilitated IVF (Laser-IVF) are presently routine procedures in human assisted reproduction. The safety of these methods at the epigenetic level is not fully understood. Studies on mouse Laser-IVF embryos provide evidence that the use of Laser-IVF leads to reduced birth rate, indicating a potential harm of this technique for the embryo. Hence, the aim of this study was to examine the difference in DNA methylation pattern between IVF- and Laser-IVF-derived mouse zygotes. We examined two experimental groups of C3HeB/FeJ oocytes: (1) zona-intact and (2) laser-microdissected oocytes that were fertilized in vitro with freshly collected spermatozoa. Zygotes were fixed 5, 8, and 12 h after fertilization, and indirect immunofluorescence staining was studied using an anti-5-methylcytidine (5-MeC) antibody. The fluorescence intensities of paternal and maternal pronuclei were evaluated using the computer-assisted analysis of digital images. In addition, we performed a semiquantitative RT-PCR analysis of the presence of transcripts of three developmental marker genes, Oct4, Dab2, and Dnmt3b, in IVF- and Laser-IVF-derived blastocysts. We observed no significant differences in methylation status of the paternal genome and in the transcripts of the developmental marker genes after IVF and Laser-IVF. In conclusion, epigenetic patterns and early embryonic development are not altered by laser-assisted IVF techniques and another explanation must be sought for the poor implantation rates observed in mice.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • DNA Methylation*
  • Embryo, Mammalian
  • Embryonic Development*
  • Female
  • Fertilization in Vitro
  • Gene Expression Regulation, Developmental
  • Humans
  • Male
  • Mice
  • Mice, Inbred C3H
  • Microdissection
  • Pregnancy
  • Zona Pellucida / metabolism*
  • Zygote / cytology
  • Zygote / growth & development
  • Zygote / metabolism*