Endoderm is the innermost of the three primary
germ layer
A germ layer is a primary layer of cells that forms during embryonic development. The three germ layers in vertebrates are particularly pronounced; however, all eumetazoans (animals that are sister taxa to the sponges) produce two or three pr ...
s in the very early
embryo
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...
. The other two layers are the
ectoderm
The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from t ...
(outside layer) and
mesoderm
The mesoderm is the middle layer of the three germ layers that develops during gastrulation in the very early development of the embryo of most animals. The outer layer is the ectoderm, and the inner layer is the endoderm.Langman's Medical E ...
(middle layer). Cells migrating inward along the
archenteron form the inner layer of the
gastrula, which develops into the endoderm.
The endoderm consists at first of flattened cells, which subsequently become columnar. It forms the
epithelial lining of multiple systems.
In
plant biology, endoderm corresponds to the innermost part of the
cortex (
bark
Bark may refer to:
* Bark (botany), an outer layer of a woody plant such as a tree or stick
* Bark (sound), a vocalization of some animals (which is commonly the dog)
Places
* Bark, Germany
* Bark, Warmian-Masurian Voivodeship, Poland
Arts, ...
) in young
shoots and young
roots often consisting of a single
cell layer. As the
plant becomes older, more endoderm will
lignify.
Production
The following chart shows the
tissues produced by the endoderm.
The embryonic endoderm develops into the interior linings of two tubes in the body, the digestive and respiratory tube.
and