Chromosomal Abnormalities in Embryos

ABSTRACT

From patients with a poor prognosis of pregnancy, 1620 embryos generated in vitro and chromosomal analysis was performed on these embryos. The result was yielded in 1596 embryos, out of them 536(34%) were euploid and 1060(66%) carried chromosomal abnormalities. In addition, 92% of embryos with multinucleated cells were diagnosed mosaics whereas the 86% of chromosomal abnormalities were associated to the presence of cytoplasmic concentration. For the derivation of the normal embryonic stem cell (ESC)lines and developmental modelling aneuploid embryos have been used. Genetic diagnosis at the cleavage or blastocyst stage could be partly abnormal because during the preimplantation diploid- aneuploid mosaic embryos was most frequently observed. From a single cell of a particular embryo the chromosomal status of that embryo can be determined, thus the prevalence of mosaicism. Detection of aneuploidy in single cells have been developed recently. After conducting research methods, it was confirmed that aneuploidy is a common feature of human oocytes and preimplantation embryos. The detection of segmental aneuploidy is currently considered problematic for embryo diagnosis and patient counselling, so the data are of great relevance for preimplantation genetic testing. The first major milestone in early mammalian embryogenesis was the formation of a totipotence blastocyst which is capable of implantation. The whole chromosomal abnormalities, or aneuploidy, determines whether the human embryos will arrest or reach the blastocyst stage. Certain embryos can still form blastocyst depending on the type of chromosomal abnormalities and that can be morphologically indistinguishable from chromosomally normal embryos.