Epigenetics and chromosome segregation in human pre-implantation embryos

Abstract

Abstract Chapter 1 Currently, the average pregnancy rate per embryo transfer after in vitro fertilization (IVF) is around 32%. In order to achieve better results in the future, we need to gain knowledge on all aspects of the treatment, including pre-implantation embryo development. In this thesis, we describe the research we performed into epigenetics and chromosome segregation in human pre-implantation embryos derived from IVF. The term ‘epigenetics’ refers to heritable marks on the genome, such as DNA methylation and histone modifications. These marks are essential for chromosome structure, chromosome segregation and gene expression. Chromosome segregation is the process in which duplicated chromosomes are equally separated over two cells during cell division. Chromosomal abnormalities are detected at high frequencies in human pre-implantation embryos. This suggests that mechanisms regulating chromosome segregation are less functional during the first cell divisions of an embryo. Next to that, epigenetic marks, which are also important for correct chromosome segregation, are different in oocytes and spermatozoa and need to be re-established in early embryos. The research described in this thesis aimed to investigate both the mechanisms regulation chromosome segregation and the re-establishmen