|
The choroid plexus (ChP) is a part of the blood-brain barrier, which shields the central nervous system (CNS) from harmful chemicals. It is a network of blood vessels and cells that are present in the ventricles of the brain. It secretes cerebrospinal fluid (CSF), which nourishes and protects the brain and spinal cord.
Understanding the function and structure of the choroid plexus helps in learning about its role in cerebrospinal fluid (CSF) production and regulation of brain homeostasis. In this article, we will cover the choroid plexus in detail.
What is Choroid Plexus?
Choroid is derived from the Greek word ‘choroids’ which means skin-like. The choroid plexus, also known as the “plica choroidea,” is a collection of specialised cells that surround a capillary and border the membrane of the pia mater and ventricles. It is involved in neuro-endocrine, neuro-immune, and excretory functions. Choroid plexus produces cerebrospinal fluid (CSF), a clear fluid that cushions the brain and spinal cord, provides nutrients, and removes waste products. The choroid plexus consists of a rich blood supply and epithelial cells that actively transport substances into and out of the cerebrospinal fluid, contributing to the brain’s overall homeostasis and function.
Choroid Plexus Location
The choroid plexus is located within the brain’s ventricles, specifically in the lateral, third, and fourth ventricles of the human brain. It is found in the frontal or occipital horn of the lateral ventricles and the cerebral aqueduct. Choroid plexus is a capillary-rich membrane that runs along a portion of the ventricles’ inner layer and it only exists in the central nervous system.
The blood-CSF or blood-brain barrier, includes the choroid plexus. Cells of the choroid plexus produce cerebrospinal fluid at the top of the lateral ventricles, through a gap known as the foramen of Monro, along the top of the third ventricle, and in a tiny piece of the fourth ventricle.
Structure of Choroid Plexus
The choroid plexus made up of epithelial cells (cuboidal) that surround capillaries and loose connective tissue.
- The choroid plexus epithelium is continuous with the ventricular layer lining the ventricular system.
- Progenitor ependymal cells are monociliated but develop into multiciliated ependymal cells.
- Unlike the ependyma, the ChP epithelial layer includes tight junctions between the cells on the ventricle side.
- These tight junctions prevent the chemicals from passing the cell layer into the cerebrospinal fluid thus acts as a barrier.
- The choroid plexus divides into multiple villi around each capillary that results in a frond-like structure which protrude into the ventricles.
- The villi and microvilli enhances the surface area of the ChP. Cerebrospinal fluid is formed when plasma from the blood is filtered through the epithelial cells.
- The epithelial cells of the choroid plexus actively transfer sodium ions into the ventricles maintating the osmotic gradient.
The main stuctures are:
|
Structure
|
Function
|
|
Epithelial cells
|
Specialized in cerebrospinal fluid production and control
|
|
Blood vessels
|
Provide nutrients and eliminates waste
|
|
Stromal tissue
|
Provide structural support and stability for the ChP
|
|
Cilia and the microvilli
|
Promote fluid flow and circulation throughout the ventricles
|
Function of Choroid Plexus
The function of choroid plexus are given below
|
Function
|
Description
|
|
CSF Production and Regulation
|
The ChP actively produces and secretes cerebrospinal fluid that protects the brain and spinal cord. It modulates the CSF composition (concentration of ions, proteins, and other solutes) so as to provide a stable chemical environment for neuronal activity.
|
|
Barrier Function
|
It is a selective barrier that regulates the transfer of chemicals between the circulation and cerebrospinal fluid thereby protecting the brain from antagonistic compounds.
|
|
Waste Clearance
|
Helps to remove metabolic waste products and toxins from the brain.
|
|
Nutrient and Hormone Transport
|
The choroid plexus transfers nutrients such as glucose, amino acids along with hormones and signalling molecules from the blood into cerebrospinal fluid where they nourish the brain and link with the other body parts.
|
|
pH Regulation
|
The choroid plexus regulates the pH of the cerebrospinal fluid, keeping it within the ideal range for neuronal activity and metabolic functions.
|
|
Immune Surveillance
|
It helps in immune surveillance inside the central nervous system, detecting and responding to pathogens, infections, and inflammatory reactions. It aso acts as nuroprotectant.
|
Choroid Plexus Cyst
Choroid plexus cysts are fluid-filled sacs that develop within the choroid plexus. These cysts are usually benign and often asymptomatic, meaning they do not cause noticeable symptoms. Choroid plexus cysts typically form during fetal development, often appearing in the second trimester of pregnancy. They are commonly detected during prenatal ultrasounds or brain imaging scans. While they usually do not require treatment and tend to resolve on their own, monitoring may be recommended in certain cases, especially if there are concerns about associated conditions or complications. Choroid plexus cysts are generally considered a normal variant of brain development and are not associated with significant health risks.
Some of the major diseases are listed below:
- Hydrocephalus: It is the abnormal accumulation of CSF in brain ventricles. Dysfunction of the ChP, which produces CSF, can lead to hydrocephalus.
- Choroid plexus Carcinoma: A rare and aggressive malignant tumor that arises from the choroid plexus tissue in the brain. It tends to occur more commonly in children and requires prompt treatment, often involving surgery, chemotherapy, and radiation therapy.
- Choroid Plexus Papilloma: A benign tumor originating from the choroid plexus in the brain’s ventricles. Although generally non-cancerous, it can obstruct the flow of cerebrospinal fluid and may require surgical removal to alleviate symptoms and prevent complications.
- Choroid Plexus Calcification: Refers to the accumulation of calcium deposits in the choroid plexus tissue of the brain. While often asymptomatic and detected incidentally on imaging studies, extensive calcification may be associated with certain medical conditions or aging processes, requiring further evaluation and monitoring
- Choroid Plexus Tumors: These are uncommon neoplasms that arise from the choroid plexus epithelium. They can cause excessive CSF production, restriction or alteration of CSF.
- Meningitis: It is an inflammation of the meninges and the spinal cord. Meningitis can be caused by bacterial or viral infections.
- Intraventricular Hemorrhage: It is bleeding in the brain’s ventricular system, including the choroid plexus lined ventricles. It affects CSF production and circulation, resulting in hydrocephalus and other neurological problems.
Conclusion – Choroid Plexus
Hence, the choroid plexus emerges as a fascinating functional nexus within complex environment of the brain. Information about the location, structure, functions, and various diseases highlights its critical role in sustaining brain health and realted function. Understanding of the choroid plexus may help in finding potential medicines and medical interventions to restore neurological health and support human health.
Also Read:
FAQs on Choroid Plexus
Where is the Choroid Plexus Located in Humans?
The choroid plexus is located in the ventricular system of a human brain. To be specificit is located in the lateral, third, and fourth ventricles but it can be found in all the ventricles of the brain.
Describe the Structure of the Choroid Plexus?
The choroid plexus consists of a network of blood vessels which is covered by ependymal cells. This region is responsible for forming a barrier which is known as the blood-cerebrospinal fluid barrier or simply the blood brain barrier.
What is the Main Function of the Choroid Plexus?
The choroid plexus is known to produce and secrete cerebrospinal fluid (CSF) which regulates its composition, and it also contributes to homeostasis in brain by removing metabolic wastes and other toxins.
What Happens if the Choroid Plexus is Damaged?
Damage to the choroid plexus can disrupt the production of cerebrospinal fluid (CSF), leading to conditions like hydrocephalus or decreased CSF flow.
What is Choroid Plexus in Fetus?
In a fetus, the choroid plexus is responsible for producing cerebrospinal fluid and regulating its composition, aiding in brain development.
What is Choroid Plexus Calcification?
Choroid plexus calcification refers to the accumulation of calcium deposits in the choroid plexus tissue, often detected incidentally on imaging scans and usually benign, though extensive calcification may be associated with certain medical conditions.
|
