<Tr> <Th> Myelin sheath </Th> </Tr> <Tr> <Td> Dendrite Soma Axon Nucleus Node of Ranvier Axon terminal Schwann cell Myelin sheath </Td> </Tr> <P> Myelin is a fatty white substance that surrounds the axon of some nerve cells, forming an electrically insulating layer . It is essential for the proper functioning of the nervous system . It is an outgrowth of a type of glial cell . </P> <P> The production of the myelin sheath is called myelination or myelinogenesis . In humans, myelination begins early in the 3rd trimester, although little myelin exists in the brain at the time of birth . During infancy, myelination occurs quickly, leading to a child's fast development, including crawling and walking in the first year . Myelination continues through the adolescent stage of life . </P>

Where is the myelin sheath located on a neuron