Endoderm

Endoderm is one of the three primary germ layers in the very early embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer), with the endoderm being the innermost 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.

Development

The endoderm produces tissue within the lungs, thyroid, and pancreas. The endoderm not only creates a number of tissues, but it also forms the linings of many systems. During the development of the embryo, some cells differentiate from the endoderm and create organs. This process is called organogenesis.

Function

The endoderm serves as the lining of the gastrointestinal tract and its associated structures. It also forms vital parts of the body's major organ systems, including the respiratory system, digestive system, and urinary system.

Clinical significance

Defects in the formation of the endoderm or in the organs it forms can lead to a number of medical conditions. For example, cystic fibrosis is a condition that affects organs that develop from the endoderm, such as the lungs and pancreas.

See also

• Ectoderm
• Mesoderm
• Organogenesis
• Germ layers
• Embryo

References

• Embryonic origin of endoderm
  Embryonic origin of endoderm
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  Gray's Anatomy illustration 21
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  Gray's Anatomy illustration 32