Fourth layer of meninges
Robert Klatt
SLYM membrane in the human brain
)alP ainigriV dnu ksuK retePnehcsneM sed nriheG mi narbmeM-MYLS(Photo: ©
- Im human brain became one by accident fourth layer of meninges discovered
- Die Subarachnoidal Lymphatic-like Membrane (SLYM) contains immune cells and prevents larger molecules from getting inside the brain
A new anatomical structure was accidentally discovered in the human brain that could be central to the organ’s fluid balance and immune protection. The fourth layer of meninges prevents larger molecules from getting inside the brain and contains immune cells.
New York (U.S.A.). In recent years, the Science several previously unknown structures in the body of the People discovered, including about a muscle in the jaw such as the tubarius glands, an organ at the entrance of the Eustachian tube. researcher of University of Rochester Medical Center and the University of Copenhagen now happen to have another anatomical structure in the human Brain discovered.
According to their publication in the specialist magazine Science the scientists actually wanted to investigate how the cerebrospinal fluid moves through the meninges. In their experiment, they mixed a fluorescent marker into the cerebrospinal fluid of mice in order to be able to observe their movement through the brain using two-photon microscopy.
Fourth meningeal layer discovered
In the space between the innermost meninges and the middle meninges (subarachnoid space), they discovered a fourth, very thin but continuous meninges that was previously unknown.
“This layer divides the subarachnoid space into an outer, superficial compartment and an inner, deeper area surrounding the brain.”
The so-called subarachnoidal lymphatic-like membrane (SLYM) also exists in humans. The meningeal layer is only a few cell layers thick and resembles the mesothelium, a membrane that surrounds the internal organs of humans.
barrier function for proteins
Although the recently discovered layer of meninges is very thin, it fulfills an essential barrier function because most molecules cannot pass through it, according to tests with colored particles.
“SLYM therefore inhibits the exchange of most peptides and proteins – including beta-amyloid and tau proteins – between the outer and inner part of the subarachnoid space.”
Cerebral fluid separation system?
According to the researchers led by Kjeld Møllgård, it is conceivable that the newly discovered meningeal layer separates clean, fresh cerebrospinal fluid from old cerebrospinal fluid. As Maiken Nedergaard explains, the find proves the important role of the liquid in the mind.
“The discovery of a new anatomical structure that controls and partitions the flow of cerebrospinal fluid in and around the brain underscores the important role of cerebrospinal fluid.”
In addition, the SLYM shell contains larger amounts of defense cells of the immune systemincluding dendritic cells for detecting enemies and macrophages.
“This suggests that the SLYM also serves as a niche for immunological monitoring.”
The SLYM membrane could also serve as a sliding layer by reducing the friction between the cranial bone and the brain during strong head movements.
Damage to the protective layer of the brain
If the brain’s protective SLYM membrane is damaged, it could affect the brain’s sewage system and immune system. Potentially harmful contaminants found in the old brain fluid could then make their way into the inner subarachnoid space and even into the brain. A crack in the protective layer would also interrupt important flow channels.
“This could explain the disturbed flow patterns of the glymphatic system after a traumatic brain injury.”
The researchers also think it is possible that the increased risk of Alzheimer’s or neuro-inflammatory complications after a severe concussion is linked to a rupture in the SLYM membrane. In animal experiments, they were able to prove that damage to the protective layer leads to inflammation and triggers a local accumulation of immune cells.
Science, doi: 10.1126/science.adc8810