The fine structure of human germ layers in vivo: clues to the early differentiation of embryonic stem cells in vitro

The fine structure of the three germ layers in human ectopic embryos (stage 7) have been documented by digital light and electron microscopy. The formation of ectoderm, endoderm and mesoderm and notochordal cells, and also the extraembryonic membranes, amnion and yolk sac, are imaged. The germ layers give rise to all the cells and tissues of the human body. Possible clues to the early differentiation of embryonic stem cells (ESC) in vitro were obtained, since these events are more or less mimicked in cultures of ESC derived from the inner cell mass of human blastocysts. The findings are discussed with reference to previous studies on the fine structure of ESC using the same technique. The fine structure of the three germ layers of the week three human embryo has been documented. These germ layers give rise to all the cells and tissues of the human body. They are the blueprints from which embryonic stem cells are formed later on in development and would be useful to those who are involved in stem cell biotechnology.