The first few days of embryonic development are a critical point for determining the failure or success of a pregnancy. Because relatively few cells make up the embryo during this period, the health of each cell is vital to the health of the overall embryo. But often, these young cells have chromosomal aneuploidies—meaning, there are too many or too few chromosome copies in the cell. Aneuploid cells lead to the failure of the pregnancy, or cause developmental defects such as Down syndrome later in gestation.
Using mouse embryos, scientists from the laboratory of Magdalena Zernicka-Goetz, Caltech’s Bren Professor of Biology and Biological Engineering, have discovered that embryos are able to rid themselves of abnormal cells just before and soon after implantation into the uterus, thereby keeping the whole embryo healthy. The research is described in a paper appearing in Nature Communications on June 11.