BioScience Dictionary

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Ot.

Found Ectoderm 12 times.

Displaying results 1 to 10.

1. Coelom
An internal fluid-filled body cavity (other than the gut) within an organism; it lies between the gut (derived from the endoderm ) and the outer body wall (derived from the ectoderm ) and is lined entirely with tissue derived from the mesoderm . It is formed from the mesoderm during embryo nic development. It is found in triploblastic animals called coelomate s.

2. Diploblastic
Describes an animal which, as an embryo , had two distinct embryonic tissue layers - the ectoderm and endoderm . This is in contrast to animals which are triploblastic (has three distinct tissue layers) and those which do not have any distinct tissue layers as an embryo (nor organs and distinct tissues as an adult). Jellyfish and comb jellies are diploblastic animals.

3. Ectoderm (ectoblast, epiblast)
The outermost layer of tissue in a developing animal embryo which will eventually become the skin and/or other outer surface of the organism, the outermost parts of the nervous system, and various other outer and external organs, structures, and systems (depends on the organism). Occurs in all animals except for sponges and placozoans.

4. Ectoderm
The outer layer of cells in embryonic development; gives rise to the skin, brain, and nervous system . Also, the outermost tissue layer in flatworms.

5. Ectomere
A blastomere (one of the cells formed during the first few divisions of the zygote ) which takes part in forming the ectoderm (the outermost tissue layer of an embryo ).

6. Exoskeleton
* A skeleton, or support structure, which supports the organism's body from the outside and is formed from the ectoderm . All arthropods (spiders, insects, crustacean s, horseshoe crabs, etc.) possess one. Compare endoskeleton . * Any structure that is formed from the ectoderm in vertebrates, like nails, claws, hair, fur, horns, or teeth. (Note: does not include skin, which is an organ.)

7. Gastrula
A hollow ball of cell s with one part of the ball pushed into the interior blastocoele (called an invagination). This early stage of animal embryonic development forms just after the blastula stage. By the end of the gastrulation process, the different embryonic germ layer s ( endoderm , ectoderm , and sometimes mesoderm ) can clearly be identified.

8. Gastrulation
A process during early embryonic development in animals in which large-scale cell migration occurs and different cell types emerge to form the germ layer s ( endoderm , ectoderm , and sometimes mesoderm ). The stage takes place just after the blastula stage and begins with an invagination (indenting) of the hollow ball of cells. During this process, the embryo is called a gastrula .

9. Germ layer
A layer of cell s produced during the process of gastrulation during the early development of the animal embryo , which is distinct from other such layers of cells, as an early step of cell differentiation . The three types of germ layers are the endoderm , ectoderm , and mesoderm .

10. Neural tube
A tube of ectoderm in the embryo that will form the spinal cord.

View web definitions »

Learn more about Ectoderm »