The Epic Interactive Encyclopedia 1997/The_Epic_Interactive_Encyclopedia_97.iso/g/germ_layer/infotext

Text File | 1992-09-03 | 409b | 11 lines

In embryology, a layer of cells that can be
distinguished during the development of a
fertilized egg. Most animals have three such
layers: the inner, middle, and outer. The
inner layer (endoderm) gives rise to the gut,
the middle one (mesoderm) develops into most
of the other organs, while the outer one
(ectoderm) gives rise to the skin and nervous
system. Simple animals, such as sponges, lack
a mesoderm.