Phagocytic cells in the CNS are
**Core Concept**
Phagocytic cells in the central nervous system (CNS) are specialized immune cells responsible for removing dead cells, foreign substances, and other debris. These cells play a crucial role in maintaining the integrity and function of the CNS.
**Why the Correct Answer is Right**
The correct answer is **Microglia**. Microglia are the resident phagocytic cells of the CNS, derived from the yolk sac and present in the brain and spinal cord from early embryonic development. They are the first line of defense against infections and injuries in the CNS, responding to pathogens, dead cells, and other harmful substances by engulfing and digesting them. Microglia express specific receptors, such as CD11b and CD68, which facilitate phagocytosis.
**Why Each Wrong Option is Incorrect**
**Option A:** Not applicable, as this option is missing.
**Option B:** Not correct, as astrocytes are a type of glial cell involved in supporting neurons, but not phagocytic functions.
**Option C:** Not correct, as oligodendrocytes are responsible for myelination of neurons, not phagocytosis.
**Clinical Pearl / High-Yield Fact**
Microglia are a key component of the CNS immune response, and their activation can contribute to neuroinflammation and neurodegenerative diseases, such as Alzheimer's and Parkinson's.
**Correct Answer:** C. Microglia.