The choroid plexus is an intricate network of ependymal cells and capillaries present prominently in the ventricles of the cerebrum in the human brain. It provides a safety barrier to the brain and the central nervous system. It also produces cerebrospinal fluid and saves the CNS from any kind of toxicity. In this article, we will study its location, structure, and important functions.
Our brain is an intricate system of nervous tissues and ganglions leading to the finest structure that enables us to do all our functions. This complex organ is well protected from the toxins, pathogens, and byproducts of metabolism by the cerebrospinal fluid and blood circulation. One such important part of the brain that aids in maintaining the health and functioning of the human brain is the choroid plexus.
By definition, it is the formation of specific tissues and cerebrospinal fluid inside the ventricular system of our brain. It means that a series of hollow spaces that are interconnected with each other and filled with cerebrospinal fluid is termed as plica choroidea or choroid plexus. It consists of modified and transformed ependymal cells that surround a network of connective tissues and capillaries.
Now that we know what choroid plexus is, let us proceed to find its location. It is present in the lateral, 3rd, and 4th ventricles of the human brain. They always remain within the meninges of the brain producing a major part of the cerebrospinal fluid.
Meninges are the membranous lining that covers and protects the central nervous system from shock, pathogens, and injuries. These meninges have three different layers, pia mater, arachnoid mater, and dura mater. The innermost layer of the meninges is the pia mater. Choroid tissues can also be found in this innermost layer as it shelters the spinal cord and cerebral cortex.
As mentioned earlier, the choroid plexus is made of specialized ependymal cells or epithelial cells surrounding the cells of loose connective tissues and a network of blood capillaries. The special feature of this epithelial tissue is the presence of cilia or hair-like projections. These projections create a case enclosing the choroid plexus. The same type of epithelial cells also creates a covering over the cerebral ventricles and central canal of the spinal cord.
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If you recall, you will remember that the spinal cord is also filled with cerebrospinal fluid. It means that these cells are also creating this fluid inside the spinal cord in the same way they are doing it inside the ventricles of the brain. From this, we can easily confirm the choroid plexus location.
These altered or transformed epithelial cells can also be considered a genre of nervous tissues termed neuroglia. They help in producing a major part of the cerebrospinal fluid circulating in the brain ventricles and the central canal of the spinal cord.
This organization of specialized epithelial cells promotes brain development. As it covers the empty spaces and central canals of the central nervous system, it provides nutrition and a medium to connect the neighbouring sections.
As mentioned earlier, the capillary network present in this tissue organization secretes cerebrospinal fluid filling the cavities and giving a proper shape to the central nervous system. The ependyma tissue is responsible for the separation of the blood capillaries from the ventricles for regulating what is entering the cerebrospinal fluid.
This fluid, on the other hand, keeps the entire brain safe and supplies nutrition for its growth. In fact, the waste products are also filtered by the choroid plexus resulting in a safe environment for the brain cells by blocking the toxic byproducts of metabolism present in the blood.
These empty spaces are filled with this fluid giving the brain and the spinal cord proper strength and support. It also provides defensive measures extracting them from the blood capillaries to protect the brain and spinal cord from toxic substances and pathogens in the blood. Lymphocytes, dendritic cells, and macrophages enter the fluid through the choroid plexus and form a defence system inside the brain and spinal cord. This is the prime choroid plexus function that forms the blood-brain barrier.
Choroid Plexus Cyst
This is a disease where a cyst forms in the choroid plexus layer of an unborn baby inside a mother’s womb. It can be a small buildup in the brain region occurring in almost 2% of the pregnancies during the 2nd trimester. It can be detected using specific choroid plexus cyst radiology techniques. In most cases, this cyst clears up before a baby’s birth and does not need any medical intervention.
If it persists, a choroid plexus cyst causes intellectual disabilities and problems in kidneys, heart, brain, etc. If it persists after birth, it can also result in a stillborn baby during birth. The size of this cyst should be watched using detailed imaging techniques.
Choroid Plexus Papilloma
It is a genre of brain tumour and is considered benign in nature. It is common in the young but rarely seen in adults. They grow quite slowly and do not spread to other parts of the body. A detailed imaging scan can detect its presence.
Choroid Plexus Calcification
The deposition of iron and calcium in this tissue inside the brain and spinal cord leads to calcification. It progresses with age and can be diagnosed using CT scans.
This is what you need to know about the choroid plexus, its location, structure, and functions. It is the prime protective barrier that saves our central nervous system from pathogens and toxic byproducts and provides nutrition.
1. What is the blood-brain barrier?
Commonly termed as BBB, it is the prime protection of the brain and the other parts of the central nervous system provided by the choroid plexus. This is a unique micro-vascular endothelial system present inside the brain offering a protective shield to stop toxic substances from entering the brain. It also acts as a shield to protect brain from pathogenic invasions. It also works as a supplier of nutrition to the brain cells.
2. What kind of immune cells are present inside the cerebrospinal fluid?
White blood cells such as lymphocytes, macrophages, and dendritic cells are present in the cerebrospinal fluid. These immune cells can travel through the endothelial barrier from the blood vessels to all parts of the brain providing protection from any harmful substance or pathogens entering the central nervous system. These cells carefully destroy the harmful substances without harming the brain.