Which of the following is associated with ependy¬mal cells rather than microglial cells?
**Core Concept**
Ependymal cells and microglial cells are two distinct types of glial cells found in the central nervous system (CNS). Ependymal cells form a single layer lining the ventricles and the central canal of the spinal cord, while microglial cells are a type of immune cell that play a crucial role in the CNS's immune response.
**Why the Correct Answer is Right**
Ependymal cells are involved in the production of cerebrospinal fluid (CSF) and are also responsible for maintaining the integrity of the blood-cerebrospinal fluid barrier. They express specific markers such as GFAP (glial fibrillary acidic protein) and are crucial for the development and maintenance of the CNS. In contrast, microglial cells are involved in the phagocytosis of debris and pathogens, and express markers such as Iba1 (ionized calcium-binding adapter molecule 1).
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the question, as it does not specify a cell type associated with either ependymal or microglial cells.
**Option B:** Microglial cells are the primary immune cells in the CNS, making this option incorrect.
**Option C:** Astrocytes are another type of glial cell, and while they are involved in various functions such as maintaining the blood-brain barrier and providing support to neurons, they are not associated with ependymal cells specifically.
**Option D:** Oligodendrocytes are involved in the myelination of neurons, but are not directly associated with ependymal cells.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that ependymal cells line the ventricles and central canal, and their dysfunction can lead to disorders such as hydrocephalus. Additionally, microglial cells play a crucial role in the pathogenesis of neurodegenerative diseases.
**Correct Answer:** C. AQP4 (aquaporin 4) is a marker associated with ependymal cells, which are involved in the production and regulation of cerebrospinal fluid.