Ans. Ectoderm and endoderm are the germ layers of the embryo. The ectoderm is the outermost layer of the embryo. It develops the largest organ of body skin, sweat glands, hair follicles, nervous system, the lining of mouth and anus, and other organs and systems. The endoderm is the innermost layer of the embryo. It develops into various organs like lungs, pancreas..etc. The anterior visceral endoderm plays a most important role in establishing anterior-posterior polarity in the mouse embryos.