Question

Which of the following forms myelin sheath in the PNS?

• A. Microglia
• B. Oligodendrocytes
• C. Neurolemmocytes
• D. Astrocytes

Answer 1

The correct option is C Neurolemmocytes

Neurolemmocytes is another name for Schwann cells. They form the myelin sheath (medullary sheath) which help form an insulating layer around the neurons of the peripheral nervous system (PNS). They are absent in the central nervous system (CNS). These are C-shaped cells which start to function in the embryonic stage itself. The plasma membrane of the Schwann cells is called neurilemma/sheath of schwann cells.

Astrocytes are star shaped cells which form the blood-brain barrier. They help in the defence and repair of nervous tissue.

Oligodendrocytes form the myelin sheath (medullary sheath) around the neurons of CNS. They consist of several cytoplasmic projections that extend to many neurons. 1 oligodendrocyte covers the axons of many neurons.

Microglia are brain macrophages that destroy dead and damaged cells. They are small and help in phagocytosis.