Myelin sheath which insulates most axons in CNS is produced by ________?

Correct option is A

The correct answer is Oligodendrocytes. Oligodendrocytes are the type of glial cells responsible for producing the myelin sheath in the central nervous system (CNS).

Information Booster:

Myelin Sheath in the CNS and PNS:
-The myelin sheath is a fatty layer that surrounds the axons of neurons, providing insulation and enhancing the speed of electrical signal transmission. Myelin allows for the rapid conduction of nerve impulses along the axon through a process known as saltatory conduction, where the electrical impulses "jump" from one node of Ranvier (the gaps in the myelin sheath) to the next, rather than traveling continuously along the axon.

Myelin in the CNS (Central Nervous System):
-Produced by: Oligodendrocytes are the specialized glial cells responsible for producing the myelin sheath in the CNS.
-Key Features:
-    Oligodendrocytes can myelinate multiple axons at once. Unlike Schwann cells in the PNS, which myelinate one axon at a time, oligodendrocytes can extend their processes to myelinate segments of several different axons.
-    Myelin produced by oligodendrocytes is critical for efficient neural communication in the brain and spinal cord, enabling faster transmission of nerve impulses across long distances.
-    Myelin in the CNS is found surrounding axons in areas such as the cerebral cortex, spinal cord, and other parts of the nervous system.
-    Diseases such as multiple sclerosis (MS) are associated with the demyelination of the CNS, leading to impairments in motor control, sensation, and cognitive function.
-    The structure of the myelin sheath in the CNS is crucial for high-speed communication between neurons, supporting functions like movement, cognition, and sensory perception.
-Pathological Consideration:
-    In multiple sclerosis (MS), the immune system attacks and damages the myelin in the CNS, leading to slower conduction of nerve impulses and a wide range of neurological symptoms, such as numbness, vision problems, and motor impairments.

Myelin in the PNS (Peripheral Nervous System):
-Produced by: Schwann cells are responsible for producing the myelin sheath in the PNS.
-Key Features:
-    Schwann cells myelinate individual axons in the PNS. Each Schwann cell wraps around a single axon segment, forming the myelin sheath.
-    The myelinated segments of axons in the PNS are separated by nodes called nodes of Ranvier, where the action potentials jump from node to node, increasing the speed of conduction.
-    Myelin in the PNS allows for faster nerve transmission, which is critical for the proper functioning of sensory and motor functions.
-    Guillain-Barré syndrome is a disorder where the immune system attacks the myelin sheath in the PNS, resulting in muscle weakness, and in severe cases, paralysis. It often follows an infection.
-    Schwann cells also play a role in nerve regeneration in the PNS, which is a key difference from the CNS, where regeneration of nerve fibers is limited.
-Regenerative Capacity:
-    In the PNS, Schwann cells can support the regeneration of damaged axons, guiding the regrowth of axonal processes after injury. In contrast, in the CNS, oligodendrocytes have a more limited capacity for axonal regeneration after injury, which is one of the reasons spinal cord injuries can be so difficult to repair.

Additional Information:
-Microglia: Microglia are the resident immune cells of the CNS, responsible for monitoring and responding to injury or infection, but they do not produce myelin.
-Astrocytes: Astrocytes are another type of glial cell in the CNS that provide structural support, maintain the blood-brain barrier, and regulate blood flow, but they do not produce myelin.