Question

Neurilemma is name for
A. Plasma-membrane of axon
B. Coating formed by Myelin Sheath
C. Covering of Schwann cells
D. Connective tissue covering of nerve fasciculus

Answer 1

Hint: The other name of Neurilemma is Neurolemmocytes. It is the outermost layer of the cytoplasm of a variety of glial cells which are basically found in neurons (nerve cells). It is found in the Peripheral Nervous System (PNS) which creates all of the neural structures outside our brain and spinal cord.

Complete Answer:
1. The plasma membrane of Axon is called the axonal plasma or the axolemma. The Axon is found in the Neurons (Nerve Cells). This is the longest part of the neurons.
2. The axon is not always sheathed by myelin. Here with this myelin, the Oligodendroglia can be synthesized and there is another thing, which is Schwann cells.
3. The Myelin Sheath provides a fat coating which surrounds the axon of the nerve cells. It can be compared with the insulator coating which wraps the electric copper wires.
4. Here we should know about fascicles. Few axons in a group together create the fascicle. Every Fascicle is covered with a layer of connective tissue which is known as Perineurium.
5. The Schwann cells cover the myelin sheath. A well-developed Schwann cell looks like a sheet of paper where the layers of Myelin sheath can be seen along every coil. The outermost layer of the Schwann cells which presents the nucleated cytoplasm. From this cytoplasm, the Neurilemma is formed. So, we can say that Neurilemma is the name of the outermost covering of Schwann Cells.

Note: In Schwann cells, both types of myelinated and unmyelinated cells can be seen. The Myelinated Schwann cells cover around the axons of motor or sensory neurons so that the myelin sheath can be formed. While the non-myelinating Schwann cells maintain axons from the outer hazards and they take crucial roles for neuronal survival especially when the myelin sheath is not there.