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The Collaborative International Dictionary

Ectoderm \Ec"to*derm\, n. [Ecto- + -derm.] (Biol.)

  1. The outer layer of the blastoderm; epiblast.

  2. The external skin or outer layer of an animal or plant, this being formed in an animal from the epiblast. See Illust. of Blastoderm.

Douglas Harper's Etymology Dictionary

1853, from ecto- + -derm. Coined by Prussian embryologist Robert Remak (1815-1865). Related: Ectodermal.


n. (label en biology) outermost of the three tissue layers in the embryo of a metazoan animal. Through development, it will produce the epidermis (skin) and nervous system of the adult


n. the outer germ layer that develops into skin and nervous tissue [syn: exoderm, ectoblast]


Ectoderm is one of the three primary germ layers in the very early embryo. The other two layers are the mesoderm (middle layer) and endoderm (most proximal layer), with the ectoderm as the most exterior (or distal) layer. It emerges and originates from the outer layer of germ cells. The word ectoderm comes from the Greek ektos meaning "outside", and derma, meaning "skin."

Generally speaking, the ectoderm differentiates to form the nervous system (spine, peripheral nerves and brain), tooth enamel and the epidermis (the outer part of integument). It also forms the lining of mouth, anus, nostrils, sweat glands, hair and nails.

In vertebrates, the ectoderm has three parts: external ectoderm (also known as surface ectoderm), the neural crest, and neural tube. The latter two are known as neuroectoderm.

Usage examples of "ectoderm".

The ectoderm creates a tube, an empty space, that becomes the spinal cord and brain.

In the normal development of the tadpole from the egg, as in all other vertebrate animals, the lens is formed from the outer skin or ectoderm of the head.

Its two epithelia, the outer and the inner, the ectoderm and the entoderm, proved to be primitive organs out of whose foldings-in and -out, were developed the glands, the tissues, the sensory organs, the body processes.

A strip of the outer germinal layer, the ectoderm, thickened, folded into a groove, closed itself into a nerve canal, became a spinal column, became the brain.