(noun. /EK-tuh-drm/)
by Yasemin Cole
What does it mean?
The ectoderm is an organism’s outer layer of cells or membrane that forms a boundary between the organism and the outside world.
This word is often used to describe how an animal (including humans) develops. Three germ layers form a multicellular organism: the ectoderm, mesoderm, and endoderm. Although the ectoderm forms the outer layer, these cells move inward into the organism through coordinated movement, forming the neural tube and neural crest cells. The neural tube eventually develops into the central nervous system (brain and spinal cord), while the neural crest gives rise to the peripheral nervous system (e.g., nerves that connect to your muscles). The nervous system controls your breathing, digestion, and skin color. The ectoderm that remains on the external surface forms structures such as the skin and hair.
The improper development of the ectoderm (from genetic mutations) can cause a number of human diseases.
How do I use it in a sentence?
“During development of an embryo, the ectoderm folds over itself to form the spinal cord, and a small subset of these cells develop into neural crest cells.”
Etymology
The Greek roots “ecto” means external or outside, and “derm” means skin or leather. A similar term is dermatology, which has the same Greek root.
History of usage
Although multiple scientists described this layer of cells, this term was coined by George James Allman, a naturalist at Trinity College, in 1853.
Related terms
Endoderm
Mesoderm
Central nervous system
Peripheral nervous system
Neural Crest
Skin
Fields of study in which this word is commonly used
Embryology
Cancer Biology
Neurology
Immunology
