Isolation of Oct4-expressing extraembryonic endoderm precursor cell lines.
BACKGROUND:The extraembryonic endoderm (ExEn) defines the yolk sac, a set of membranes that provide essential support for mammalian embryos.Recent findings suggest that the committed ExEn precursor is present already in the embryonic Inner Cell Wooden Ornament Custom Shape Mass (ICM) as a group of cells that intermingles with the closely related ep