Ectoderm
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ectoderm
[′ek·tə‚dərm] (embryology)
The outer germ layer of an animal embryo. Also known as epiblast.
(invertebrate zoology)
The outer layer of a diploblastic animal.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.
Ectoderm
(1) The outermost germ layer; the external layer of the embryo of multicellular animals in the gastrular stage. From the ectoderm are formed the integuments, nervous system, sensory organs, anterior and posterior sections of the digestive tract, external gills, and ectomesenchyme. In the Deuterostomia, all the elements derived from the ectoderm are formed as a result of the action upon it of the chordomesoderm, the entoderm, and their derivatives.
(2) The external wall of the body of coelenterates. The ectoderm consists of a single layer of cells—epithelial, epithelio-muscular, interstitial, and sensory cells, as well as stinging capsules.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.