Neuroglial Cells in the CNS and PNS

Role of Microglia

• Microglia have a protective role in the Central Nervous System (CNS).

• They sense microbes and cellular debris in the environment.

• Upon activation, microglial cells transform into macrophage-like cells to phagocytose (engulf and digest) debris, contributing to tissue maintenance and defense.

Microglial Cells

• Microglial cells are classified as defensive cells within the CNS, functioning as its primary immune surveillance components.

Ependymal Cells

• Ependymal cells line the cavities of the brain and spinal cord.

  • They are ciliated, which aids in circulating cerebrospinal fluid (CSF) throughout the CNS.

  • Ependymal cells thus play a crucial role in maintaining the homeostasis of the CSF environment.

Neuron Structure

• The neuron is composed of various types of supporting cells, including microglial and ependymal cells.

Oligodendrocytes

• Oligodendrocytes serve an essential function in the CNS by wrapping their branched extensions around large nerve fibers.

  • They provide an insulating cover known as the myelin sheath.

  • Each oligodendrocyte can myelinate approximately 60 axons, facilitating effective electrical insulation and rapid signal conduction.

  • The myelin sheath has gaps called Nodes of Ranvier which are crucial for saltatory conduction of action potentials.

Neuroglia of the Peripheral Nervous System (PNS)

• Satellite Cells:

  • Satellite cells are specific to the peripheral nervous system.

  • They wrap around neuronal cell bodies, providing support and nutrition similar to astrocytes in the CNS.

  • Their location is primarily in the peripheral nervous system, surrounding clusters of nerve cell bodies (ganglia).