endoderm n : the inner germ layer that develops into the lining of the digestive and respiratory systems [syn: entoderm, endoblast, entoblast, hypoblast]

English

Noun

1. One of the three tissue layers in the embryo of a metazoan animal. Through development, it will produce the digestive system of the adult.

See also

• ectoderm
• mesoderm

Endoderm, (sometimes called Entoderm) is one of the germ layers formed during animal embryogenesis. 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 the whole of the digestive tube except part of the mouth, pharynx and the terminal part of the rectum (which are lined by involutions of the ectoderm), the lining cells of all the glands which open into the digestive tube, including those of the liver and pancreas, the epithelium of the auditory tube and tympanic cavity, of the trachea, bronchi, and alveoli of the lungs, of the urinary bladder and part of the urethra, and that which lines the follicles of the thyroid gland and thymus.

Production

The following graph represents the products produced by the endoderm.

Additional images

See also

• Ectoderm
• Germ layer
• Histogenesis
• Mesoderm
• Organogenesis
• Endodermal sinus tumor

Notes

References

• Evers, Christine A., Lisa Starr. Biology:Concepts and Applications. 6th ed. United States:Thomson, 2006. ISBN 0-534-46224-3.