Definition of "endoderm" [en•do•derm]

• The innermost of the three primary germ layers of an animal embryo, developing into the gastrointestinal tract, the lungs, and associated structures. Also called hypoblast. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "This stage of differentiation consists in the formation of either a pouch or an additional layer between the ectoderm and the endoderm, which is called the mesoderm."
• "The endoderm is the innermost layer that lines the digestive tract."
• "It proceeded through a primitive embryonic endoderm, which clumped into embryoid bodies."