Ependymal Cells

Edited By Irshad Anwar | Updated on Jul 02, 2025 07:24 PM IST

Definition Of Ependymal Cells

Ependymal cells are a neuroglial cell type that lines the cavities of the ventricles within the brain and the central canal inside the spinal cord. The ciliated cells play an important role in generating, circulating, and regulating CSF, which, among other things, cushions the brain, removes metabolic wastes, and maintains a stable chemical environment. The ependymal cells provide a way for CSF to flow and thus protect the brain and spinal cord from hurt, providing smooth functioning of neural activity. They are, therefore, essential for the health and maintenance of the nervous system.

Structure Of Ependymal Cells

The structure of Ependymal cells is described below-

General Structure

Ependymal cells are the epithelium-like glial cells that line the ventricles of the brain and the central canal of the spinal cord. They are usually cuboidal or columnar, with cilia and microvilli on the apical surface. Their cilia circulate the CSF, and the microvilli participate in absorptive and secretory activities.

Types Of Ependymal Cells

Cuboidal or Columnar Ependymal Cells: These are the most common forms that line the ventricular system and the central canal. They form the majority of cells lining these structures and play an important role in CSF movement and homeostasis.

Specialised Ependymal Cells: They are tanycytes, localised to specific regions, for instance, within the third ventricle, that seem to have specific functions such as hormone transport and even participate in neuroendocrine signalling.

Function Of Ependymal Cells

The function of Ependymal cells are described below-

Role In The Central Nervous System

Ependymal cells play a crucial role in the formation and circulation of CSF, mechanically cushioning the brain and spinal cord, removing waste, and maintaining a very stable chemical environment. The ependymal cells are ciliated; their beats become coordinated to favour CSF flow within the ventricular system.

Barrier Function

Ependymal cells line the cavities of the central nervous system and form the blood-CSF barrier, which governs the blood-to-CSF exchange of substances. It protects the CNS from probably toxic compounds in the blood and gives a stable milieu to neural activity.

Support and Maintenance

They provide structural support to neural tissues and do associate intimately with other glial cell types to provide general maintenance and health of the nervous system. They play and could therefore have a role in the response to injury and disease through the control of neurogenesis and repair mechanisms.

Location Of Ependymal Cells

The location of Ependymal cells is described below-

Ventricular System

Ependymal cells form a continuous lining of the walls of the ventricles of the brain, where they contribute to the formation and circulation of CSF. Their position allows for the free flow and dissemination of CSF within the ventricular cavities of the brain.

Central Canal of the Spinal Cord

In the spinal cord, they line the central canal, providing a route for the circulation of CSF down the length of the spinal column. In other words, they become part of the mechanisms involved in maintaining the environment around the spinal cord—protective and nourishing.

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Frequently Asked Questions (FAQs)

1. What are ependymal cells and what is their general function?

Ependymal cells are glial cells lining the ventricles of the brain and in the central canal of the spinal cord. The primary function of these cells is the production and circulation of CSF.

2. How do ependymal cells contribute to the blood-CSF barrier?

Ependymal cells form the blood cerebrospinal fluid barrier thus helping to maintain the environment of the central nervous system and hence control the movement of the substance between blood and CSF.

3. What are some of the common diseases that involve ependymal cells?

The most common diseases include Ependymoma, a type of brain tumour originating in the Ependymal cells. The malfunction of the Ependymal cells results in impaired CSF circulation.

4. Where in the central nervous system are the ependymal cells located?

The Ependymal cells line the ventricles in the brain and the central canal in the spinal cord.

5. What are the recent trends in research concerning the ependymal cells?

Recent developments in the research of ependymal cell regeneration and their functions in neurodegenerative diseases have been reported, with emerging technologies for better understanding of these cells.

6. How do ependymal cells differ from epithelial cells in other parts of the body?

While ependymal cells form an epithelial-like layer, they differ from typical epithelial cells in several ways. They lack a basement membrane, have specialized features like cilia and microvilli, and retain some properties of neural stem cells. They also have unique functions related to CSF circulation and brain homeostasis.

7. What is the role of ependymal cells in the formation of the neural tube during embryonic development?

During early development, the cells lining the neural tube (which later becomes the ventricular system) are neuroepithelial cells. These cells eventually differentiate into radial glia, which then give rise to ependymal cells. This process is crucial for the proper formation of the ventricular system and the central canal.

8. What is the relationship between ependymal cells and cerebrospinal fluid production?

While ependymal cells do not produce the bulk of CSF (which is primarily produced by the choroid plexus), they can secrete small amounts of fluid and various molecules into the CSF. More importantly, they play a crucial role in CSF circulation and in maintaining its composition.

9. What is the relationship between ependymal cells and the circumventricular organs?

Circumventricular organs are specialized regions in the brain where the blood-brain barrier is modified or absent. Ependymal cells in these areas, often called tanycytes, have unique properties that allow for communication between the blood, CSF, and brain tissue, playing important roles in neuroendocrine function and homeostasis.

10. What is the significance of the S100β protein in ependymal cells?

S100β is a calcium-binding protein expressed by ependymal cells. It plays roles in cell proliferation, differentiation, and calcium homeostasis. The presence of S100β is often used as a marker for ependymal cells and can indicate their activation or stress response in various pathological conditions.

11. How do ependymal cells contribute to cerebrospinal fluid (CSF) circulation?

Ependymal cells have hair-like projections called cilia on their apical surface. These cilia beat in a coordinated manner to help circulate cerebrospinal fluid throughout the ventricular system and central canal, facilitating the movement of nutrients and waste products.

12. What is the blood-cerebrospinal fluid barrier, and how do ependymal cells contribute to it?

The blood-cerebrospinal fluid barrier is a selective barrier that regulates the passage of substances between the blood and CSF. Ependymal cells contribute to this barrier by forming tight junctions between adjacent cells, helping to control the movement of molecules and maintain the unique composition of the CSF.

13. How do ependymal cells help maintain the chemical balance of the cerebrospinal fluid?

Ependymal cells have specialized transport proteins in their cell membranes that allow them to selectively move ions and other molecules between the CSF and brain tissue. This helps maintain the proper chemical composition of the CSF, which is crucial for brain function.

14. How do ependymal cells respond to brain injury or inflammation?

In response to injury or inflammation, ependymal cells can proliferate and change their morphology. They may also increase the expression of certain proteins, such as glial fibrillary acidic protein (GFAP), which is typically associated with reactive astrocytes.

15. What is the function of the microvilli on ependymal cells?

Ependymal cells have numerous microvilli on their apical surface, in addition to cilia. These microvilli increase the surface area of the cells, enhancing their ability to absorb and secrete substances between the CSF and brain tissue, thus aiding in metabolic exchange.

16. What are ependymal cells and where are they located?

Ependymal cells are specialized glial cells that line the ventricles of the brain and the central canal of the spinal cord. They form a single layer of ciliated epithelium called the ependyma, which is part of the central nervous system.

17. How do ependymal cells differ from other types of glial cells?

Ependymal cells are unique among glial cells in that they form an epithelial-like layer lining the ventricles and central canal. Unlike astrocytes or oligodendrocytes, ependymal cells have cilia and are directly involved in CSF circulation and filtration.

18. What is the relationship between ependymal cells and the choroid plexus?

While ependymal cells line most of the ventricular system, the choroid plexus is a specialized structure within the ventricles that produces CSF. The choroid plexus is composed of modified ependymal cells called choroid epithelial cells, which are specialized for CSF production.

19. What is the role of ependymal cells in neurogenesis?

Some ependymal cells, particularly those in specific regions like the subventricular zone, act as neural stem cells. These cells can divide and differentiate into neurons or glial cells, contributing to adult neurogenesis in certain areas of the brain.

20. What are tanycytes, and how are they related to ependymal cells?

Tanycytes are a specialized type of ependymal cell found primarily in the third ventricle of the brain. They have long processes that extend into the hypothalamus and play important roles in neuroendocrine function, energy balance, and act as a bridge between the CSF and the hypothalamus.

21. What is the significance of the basal processes of ependymal cells?

The basal processes of ependymal cells extend into the underlying brain tissue. These processes allow ependymal cells to interact with blood vessels, neurons, and other glial cells, facilitating the exchange of substances between the CSF and brain tissue.

22. What is the glycocalyx, and why is it important for ependymal cell function?

The glycocalyx is a carbohydrate-rich layer on the surface of ependymal cells. It helps protect the cells from harmful substances in the CSF, aids in cell-to-cell adhesion, and may play a role in trapping and concentrating growth factors and other signaling molecules near the cell surface.

23. How do ependymal cells differ between the brain and spinal cord?

While ependymal cells in both the brain and spinal cord share many similarities, there are some differences. Spinal cord ependymal cells tend to have longer basal processes and may have a greater capacity for neurogenesis compared to most brain ependymal cells.

24. How do ependymal cells change during aging?

As the brain ages, ependymal cells may undergo several changes, including a reduction in number, flattening of their shape, and a decrease in ciliary function. These changes can affect CSF circulation and may contribute to age-related neurological disorders.

25. How do ependymal cells communicate with other cells in the central nervous system?

Ependymal cells can communicate with other cells through gap junctions, which allow for the direct passage of small molecules and ions between cells. They also release and respond to various signaling molecules, enabling them to interact with neurons and other glial cells.

26. How do ependymal cells respond to hypoxia or ischemia in the brain?

During hypoxia or ischemia, ependymal cells can undergo various changes. They may increase the expression of protective proteins, alter their metabolic activity, or even detach from the ventricular wall. Their response to these conditions can influence the extent of brain damage and the potential for recovery.

27. How do ependymal cells contribute to the removal of waste products from the brain?

Ependymal cells help remove waste products from the brain by facilitating the movement of CSF, which carries metabolic waste. They also have the ability to take up certain waste molecules directly from the CSF and transfer them to the blood for elimination.

28. What is the role of ependymal cells in hydrocephalus?

In hydrocephalus, a condition characterized by excessive accumulation of CSF in the brain, ependymal cells can be damaged or lost. This can disrupt normal CSF circulation and absorption, potentially exacerbating the condition. Understanding ependymal cell function is crucial for developing treatments for hydrocephalus.

29. How do ependymal cells contribute to the regulation of cerebral blood flow?

Ependymal cells can detect changes in CSF composition and pressure. Through their connections with astrocytes and blood vessels, they can indirectly influence cerebral blood flow in response to these changes, helping to maintain proper brain function.

30. What is the role of ependymal cells in the development of the central nervous system?

During embryonic development, ependymal cells are derived from radial glial cells, which serve as progenitors for neurons and glial cells. As development progresses, some ependymal cells retain stem cell properties, contributing to ongoing neurogenesis in specific brain regions.

31. How do ependymal cells respond to changes in osmolarity of the cerebrospinal fluid?

Ependymal cells have osmoreceptors that allow them to detect changes in CSF osmolarity. In response to these changes, they can alter their shape and adjust their transport of water and ions, helping to maintain the proper osmotic balance in the brain.

32. What is the significance of the tight junctions between ependymal cells?

Tight junctions between ependymal cells are crucial for maintaining the integrity of the ependymal layer. They help regulate the passage of substances between the CSF and brain tissue, contributing to the blood-CSF barrier and protecting the brain from potentially harmful substances.

33. How do ependymal cells contribute to the immune response in the central nervous system?

Ependymal cells can produce and respond to various cytokines and chemokines, allowing them to participate in the immune response within the central nervous system. They can also facilitate the movement of immune cells between the CSF and brain tissue.

34. How do ependymal cells contribute to the maintenance of cerebral homeostasis?

Ependymal cells play a vital role in maintaining cerebral homeostasis by regulating CSF circulation, participating in the blood-CSF barrier, facilitating metabolic exchange between CSF and brain tissue, and responding to changes in CSF composition and pressure.

35. What is the significance of the motile cilia on ependymal cells?

The motile cilia on ependymal cells beat in a coordinated manner to create currents in the CSF. This ciliary movement is crucial for proper CSF circulation, which helps distribute nutrients, remove waste products, and maintain the chemical and physical properties of the CSF.

36. How do ependymal cells interact with neural stem cells in neurogenic regions of the brain?

In neurogenic regions like the subventricular zone, some ependymal cells act as neural stem cells or interact closely with neural stem cells. They provide structural support, secrete factors that regulate stem cell behavior, and may even give rise to new neurons or glial cells.

37. What is the role of ependymal cells in spinal cord injury and repair?

Following spinal cord injury, ependymal cells can proliferate and migrate to the site of injury. Some of these cells may differentiate into astrocytes or other cell types, potentially contributing to the formation of glial scars. Understanding this process is important for developing therapies for spinal cord injuries.

38. How do ependymal cells contribute to the regulation of brain temperature?

Ependymal cells, through their role in CSF circulation, help distribute heat throughout the brain. They may also be involved in detecting temperature changes and initiating responses to maintain optimal brain temperature, which is crucial for proper neuronal function.

39. How do ependymal cells contribute to the clearance of beta-amyloid from the brain?

Ependymal cells play a role in the clearance of beta-amyloid, a protein associated with Alzheimer's disease, from the brain. They facilitate the movement of CSF, which can carry beta-amyloid, and may also directly take up and process this protein, potentially influencing the progression of neurodegenerative diseases.

40. What is the significance of the polarity of ependymal cells?

Ependymal cells are polarized, with distinct apical (facing the ventricle) and basal surfaces. This polarity is crucial for their function, allowing them to properly orient their cilia, distribute transport proteins, and maintain the directional flow of substances between the CSF and brain tissue.

41. How do ependymal cells respond to changes in intracranial pressure?

Ependymal cells can detect changes in intracranial pressure through mechanoreceptors. In response to pressure changes, they may alter their shape, modify their ciliary beating patterns, or release signaling molecules that can influence nearby blood vessels and other cells, helping to regulate intracranial pressure.

42. What is the role of ependymal cells in the transport of hormones within the brain?

Ependymal cells, particularly tanycytes in the third ventricle, play a crucial role in neuroendocrine function. They can take up hormones from the CSF and transport them to nearby neurons or blood vessels, facilitating hormonal signaling within the brain and between the brain and the rest of the body.

43. How do ependymal cells contribute to the regulation of neuroinflammation?

Ependymal cells can produce and respond to various inflammatory mediators. They may help regulate the entry of immune cells into the brain parenchyma and participate in the brain's innate immune response. Understanding their role in neuroinflammation is important for studying various neurological disorders.

44. What is the significance of the N-cadherin protein in ependymal cells?

N-cadherin is an important adhesion molecule in ependymal cells. It helps maintain the integrity of the ependymal layer by facilitating cell-to-cell adhesion. N-cadherin is also crucial for the proper development and organization of ependymal cells during brain development.

45. How do ependymal cells contribute to the regulation of adult neurogenesis?

In neurogenic regions like the subventricular zone, ependymal cells create a supportive niche for neural stem cells. They secrete factors that regulate stem cell proliferation and differentiation, and some ependymal cells may even act as neural stem cells themselves, contributing directly to adult neurogenesis.

46. What is the role of ependymal cells in the formation and maintenance of the blood-brain barrier?

While ependymal cells are not a direct component of the blood-brain barrier (which is formed by endothelial cells), they contribute to the blood-CSF barrier. They help regulate the exchange of substances between the CSF and brain tissue, indirectly influencing the overall barrier function of the central nervous system.

47. How do ependymal cells interact with astrocytes in the brain?

Ependymal cells and astrocytes have close interactions in the brain. The basal processes of ependymal cells often contact astrocyte end-feet. This interaction allows for the exchange of signals and metabolites, and it's crucial for maintaining the blood-CSF barrier and regulating brain homeostasis.

48. How do ependymal cells contribute to the regulation of neurotransmitter levels in the CSF?

Ependymal cells express various transporters that can take up neurotransmitters from the CSF. This helps regulate neurotransmitter levels in the CSF, which is important for maintaining proper signaling in the brain and protecting neurons from excessive neurotransmitter exposure.

49. What is the role of ependymal cells in the development and progression of brain tumors?

Ependymal cells can give rise to a type of brain tumor called ependymoma. Additionally, disruption of the ependymal layer can contribute to the spread of other types of brain tumors. Understanding ependymal cell biology is therefore important for developing treatments for certain brain cancers.

50. What is the role of aquaporins in ependymal cell function?

Aquaporins are water channel proteins expressed by ependymal cells. They play a crucial role in regulating water movement between the CSF and brain tissue. This is important for maintaining proper CSF volume and composition, and for responding to changes in osmotic pressure.

51. How do ependymal cells contribute to the circadian rhythm regulation in the brain?

Ependymal cells, particularly tanycytes in the third ventricle, play a role in circadian rhythm regulation. They can respond to and transmit signals related to light-dark cycles and metabolic states, influencing the function of the suprachiasmatic nucleus, the brain's primary circadian pacemaker.

52. What is the significance of the vimentin protein in ependymal cells?

Vimentin is an intermediate filament protein expressed by ependymal cells. It provides structural support to the cells and is important for maintaining their shape and integrity. Vimentin