Cell exclusion is not a mechanism for eliminating chromosomal abnormalities

Cell exclusion is not a mechanism for eliminating chromosomal abnormalities

A team of investigators from the Reproductive Medicine Unit of Dexeus Mujer led by Dr Mónica Parriego have conducted a study to investigate whether the exclusion of some cells during embryonic development is a natural self-correction mechanism to prevent the development of chromosomal abnormalities in the embryo.

To find out, the study included a total of 25 hatched blastocysts in which the exclusion of some cells had been observed. The investigators separately tested biopsies of the blastocyst trophectoderm under study and the excluded cells to detect any abnormalities. Specifically, they studied the chromosomal contents of the pairs tested and the concordance in the number of chromosomes.

In four cases, it was not possible to obtain genetic information on the excluded cells. Concordance in the number of chromosomes was observed in 18 of the 21 pairs tested (85.7%). The three discordant cases were mosaic embryos. Full concordance in chromosomal constitution was observed in 12 of the 21 pairs. In the remaining 6 cases, the detected aneuploid abnormality was also present in the excluded cells.

Therefore, the authors conclude that the expulsion of cells during embryo development does not appear to be related to the existence of chromosomal abnormalities.

Excluded cells during blastocyst formation: is aneuploidy the reason?
M. Parriego; L. Coll. M. Devesa. M. Boada, B. Coroleu, A. Veiga.
Department of Obstetrics, Gynaecology and Reproduction. Hospital Universitari Dexeus, Barcelona.
ESHRE 2018 poster