Animals have two or three embryonic-cell types {germ layer}|: endoderm, mesoderm, and ectoderm. Germ layers develop from coelom tubes.
Outer tube {ectoderm}| becomes senses, nerves, and outer skin.
Cells between ectoderm and endoderm {mesoderm}| become muscles and glands in three-germ-layer animals. Two-germ-layer animals have no mesoderm.
Inner tube {endoderm}| becomes digestive tract.
Outline of Knowledge Database Home Page
Description of Outline of Knowledge Database
Date Modified: 2022.0225