Endoderm

Endoderm
Organs derived from endoderm.
Blastodermic vesicle of Vespertilio murinus. (Endoderm labeled as 'entoderm'.)
Gray's	subject #6 49
Days	16
Precursor	hypoblast
Gives rise to	splanchnopleure
MeSH	Endoderm

Endoderm is one of the three primary germ cell layers in the very early embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer), with the endoderm as the intermost layer. Cells migrating inward along the archenteron form the inner layer of the gastrula, which develops into the endoderm.^{[citation needed]}

The endoderm consists at first of flattened cells, which subsequently become columnar. It forms the epithelial lining of multiple systems.^{[citation needed]}

Production

The following chart shows the products produced by the endoderm.

Layer	Category	System
General	Gastrointestinal tract.	the entire alimentary canal 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
General	Respiratory tract	the trachea, bronchi, and alveoli of the lungs
General	Endocrine glands and organs	the lining of the follicles of the thyroid gland and thymus
	Auditory system	the epithelium of the auditory tube and tympanic cavity
	Urinary system	the urinary bladder and part of the urethra

Liver and pancreas cells are believed to derive from a common precursor.

The Endoderm has differentiated into distinguishable organs as early as 5 weeks of embryonic development.

Additional images

• 

  Section through the embryo.

• 

  Section through ovum imbedded in the uterine decidua

See also

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

References

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.