Which statements describe Astrocytes (CNS)?

• A. Small; Phagocytic
• B. Wraps axons in myelin
• C. Line cavities with CSF
• D. Largest; Most numerous; Contains BBB

Answer: (D)

Astrocytes are the most numerous glial cells in the central nervous system and have star-shaped processes that wrap around neurons and blood vessels. They provide structural support, help maintain the extracellular environment by regulating ions and neurotransmitters, and critically contribute to the blood-brain barrier through their endfeet that ensheath capillaries. They also participate in repair after injury. The other descriptions refer to different cell types: phagocytic activity points to microglia, myelin wrapping is done by oligodendrocytes, and lining ventricles with cerebrospinal fluid is the job of ependymal cells. Because astrocytes are the largest, most abundant glial cells and participate in the BBB, the statement that describes them best is the one about being large, numerous, and involved with the BBB.