Endoderm

{{Short description|Inner germ layer of embryonic development}}

{{Infobox embryology

| Name = Endoderm

| Latin =

| Image = Embryonic_origin_of_endoderm.png

| Caption = Tissues derived from endoderm.

| System =

| CarnegieStage =

| Days = 16

| Precursor = Epiblast

| GivesRiseTo =

}}

Endoderm is the innermost of the three primary germ layers in the very early embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer).Langman's Medical Embryology, 11th edition. 2010. Cells migrating inward along the archenteron form the inner layer of the gastrula, which develops into the endoderm.{{cite journal |last1=Fukuda |first1=Kimiko |last2=Kikuchi |first2=Yutaka |title=Endoderm development in vertebrates: fate mapping, induction and regional specification |journal=Development, Growth and Differentiation |date=August 2005 |volume=47 |issue=6 |pages=343–355 |doi=10.1111/j.1440-169X.2005.00815.x |pmid=16109032 |s2cid=26241717 |url=https://onlinelibrary.wiley.com/doi/full/10.1111/j.1440-169X.2005.00815.x |access-date=10 March 2023 |language=en |issn=0012-1592|doi-access=free }}

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) in young shoots and young roots often consisting of a single cell layer. As the plant becomes older, more endoderm will lignify.