## **Core Concept**
Neuroglial cells, also known as glial cells, are non-neuronal cells that provide support and protection for neurons in the central nervous system (CNS). The main types of neuroglial cells in the CNS include astrocytes, oligodendrocytes, microglia, and ependymal cells. These cells are crucial for maintaining the environment around neurons.

## **Why the Correct Answer is Right**
The correct answer, , refers to Schwann cells. Schwann cells are a type of neuroglial cell but are specifically found in the peripheral nervous system (PNS), not the CNS. They are responsible for myelination of neurons in the PNS, which is essential for the proper functioning of the nervous system. This distinguishes them from the other options provided, which are all types of neuroglial cells found in the CNS.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Astrocytes are a type of neuroglial cell in the CNS and are involved in providing nutrients to neurons, maintaining the ion balance, and more.
- **Option B:** Oligodendrocytes are also CNS neuroglial cells and are responsible for the myelination of neurons within the CNS.
- **Option C:** Microglia act as the first and main form of active immune defense in the CNS, making them a type of neuroglial cell in the CNS.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that while Schwann cells are involved in myelination, similar to oligodendrocytes in the CNS, they are distinct in their location (PNS vs. CNS) and the number of axons they myelinate (one axon per Schwann cell in the PNS vs. multiple axons per oligodendrocyte in the CNS).

## **Correct Answer:** . Schwann cells