Description
The inner cell mass (ICM) of the early blastocyst at E3.5, a source of ES cell derivation, is a morphologically homogeneous population of undifferentiated pluripotent cells that give rise to all embryonic lineages. The immediate application of the newly developed V1V3 method to single cells in this stage of mouse embryos revealed the presence of two populations of cells, one with primitive endoderm expression and the other with pluripotent epiblast-like gene expression. The genes expressed differentially between these two populations were well preserved in morphologically differentiated primitive endoderm and epiblast in the embryos one day later (E4.5), demonstrating that the method successfully detects subtle but essential differences in gene expression at the single-cell level among seemingly homogeneous cell populations. This study provides a strategy to analyze biophysical events in medicine as well as in neural, stem cell, and developmental biology, where small numbers of distinctive or diseased cells play critical roles.