Answer to Question #151773 in Zoology for Chamran Kreal

Question

What is the ectoderm?

Answer 1

The germ line has the following three layers:

1. Endoderm: inner layer forms structures like digestive system
2. Mesoderm: middle layer forms structure like muscle cells
3. Ectoderm: outermost of three germ layer

ECTODERM: This term is made of two words: "ecto" and "derm". "Ecto" means outside and "derm" means skin. So, as the name suggests, ectoderm is the outer layer that covers the embryo and formed during embryogenesis. This outer layer gives rise to a number of outer organs, namely:

1. Skin
2. Sweat gland
3. Hair follicle

Other main function of ectoderm is to form central nervous system (comprise of brain and spinal chord).

The ectoderm layer has four parts:

1. External ectoderm: Also, known as surface ectoderm which forms skin, tooth enamel, etc.
2. Neural plate: It forms the basis of nervous system.
3. Neural Crest: It gives rise to the cells of smooth muscle, bone, etc.
4. Neurogenic Placodes: It gives rise to neurons and other structures of sensory neuron.

In nutshell, ectoderm is the outer layer of the embryo which differentiate to central nervous system, skin, hair follicle, etc which are present on the outer side of the body.