Final answer:
The three germ layers of the embryo from outermost to innermost are the ectoderm, mesoderm, and endoderm, each giving rise to distinct tissues and organs.
Step-by-step explanation:
The three germ layers of the embryo from outermost to innermost are the ectoderm, mesoderm, and endoderm. The ectoderm is the outermost layer that gives rise to tissues such as the nervous system and the epidermis (skin). The mesoderm is the middle layer, responsible for forming muscle cells, connective tissue, and various systems such as the circulatory system. The endoderm, being the innermost layer, develops into the internal organs like the gut, lungs, and pancreas.
The specialization of these germ layers begins after the process of gastrulation in the embryo, allowing embryonic cells to migrate and differentiate into cell lineages that will grow into mature organs and organ systems. The inner cell mass of the blastula contains embryonic stem cells which will eventually arrange themselves into these three germ layers, each contributing to specific parts of the developing organism.