Petrushko M. The morphofunctional, cytological and molecular genetic analysis of native and cryopreseved human embryos

This thesis describes the development of the principles of morphofunctional, cytological and molecular genetic analysis of embryos, including the taking into account their morphological characteristics, development stage, enabling to use for transfer into patients' uterus cavity of morpholohgically and genetically competent embryos. It has been found that optimal stage for cryopreservation of pre-implantation human embryos is zygote. Stepwise thawing of zygotes during the 1-3rd days before embryo transfer and their following culturing enables to transfer into uterus cavity the embryos of various gestation terms that allows to increase their implantation. Cryopreserved embryos in comparison with native ones are characterized with different rates of morphogenetic development. After cryopreservation the embryos demonstrate accelerated cleavage terms that is manifested in early formation of blastocyst and rise in total number of blastomeres. Cryopreservation factors induce blastomere fragmentation with theformation of nuclei-free cytoplasma sites, affect the blastocyst ability to "hatch" out of zona pellucida, increase the number of pathological state of mitoses and induce the appearance of multinuclear blastomeres. In cryopreserved embryos the frequency of aneuploidy on chromosomes of G group increases, there is a rise in the mosaics and polyploidia frequency. In this connection it has been proposed to perform pre-implantation genetic diagnostics of cryopreserved embryos.