Question

Myelin sheath is formed by
A. Ranvier cells
B. Muscle cells
C. Schwann cells
D. Axon

Answer 1

Hint: It is one part of the structure of a simplified neuron in the peripheral nervous systemPNS. It is part of the nervous system. It is also called neurolemmocytes. These cells wrapped around an axon. This cell has two types that are myelinating and non myelinating. It is involved in many important aspects of peripheral nerve biology.

Complete answer:
Myelin sheath looks like a lipid or fatty substance that surrounds the nerve cells called axons to insulate them and also to increase the rate at which the electrical impulses are passed along the axon. Schwann cells or neurolemmocytes are the head of the glia of the peripheral nervous system. The function of the glia cells is to support neurons and the peripheral nervous system, it also includes satellite cells. The two types of Schwann cells are myelinated and non myelinating.
Myelinating Schwann cells care wrapping around the axons of motors and sensory neurons to form the myelin sheath. This cell promoter is present in the downstream region of the human dystrophin gene. Schwann cells have a variety of glial cells that keep peripheral nerve fibers that are both myelinated and non myelinating alive. In that myelinated axons these Schwann cells form the myelin sheath. This is not continuous. The gap between two adjacent Schwann cells are called nodes of Ranvier.
Myelinating Schwann cells start to form a myelin sheath in mammals during fetal development and it works by spiralling around the axon. Schwann cells are very essential for maintaining the healthy axons.

Hence, the correct answer is option (C).

Note: Mostly a developed Schwann cell is shaped like a rolled up sheet of paper, that too with layers of myelin between each coil. Myelination of Schwann cells is associated with axons. Schwann cells are well known for their roles in supporting nerve regeneration. Nerves in that peripheral nervous system consist of many numbers of axons myelinated by Schwann cells.