It is called “SLYM”. This thin membrane placed between the arachnoid and the pia mater is the fourth meninge. Its role is to protect our brain through its immune, mechanical and cleansing functions.
The dura mater, the arachnoid mater and the pia mater: these three names may ring a bell. These are the three membranes that make up the meninges, this protective barrier covering our brain. But like the musketeers, our three meninges have a fourth congener, a membrane so thin that it was by chance that it was first observed in new work published in Science. Called SLYM, it has, among other things, a role of outpost of immunity and filtering of the cerebrospinal fluid bathing our cranial box.
The “glymphatic system” of the brain
The meninges are the cornerstone of the “glymphatic system”, a portmanteau word meaning that it is the so-called “glial” cells of the brain that play the role of filtering waste there, assigned to the lymphatic system in the rest of the body. They serve as a filtration system for the cerebrospinal fluid (CSF), the waste products from which are evacuated to the venous blood. “Only by using a combination of histology (study of tissue structure, editor’s note) and live imaging that we were able to obtain definitive proof of the existence of the SLYM membrane, by studying sections of whole mouse heads.”explains to Science and Future neuroscientist Maiken Nedergaard, whose lab did this work and coined the term “glymphatic system” several years earlier.
A thin membrane named SLYM, found by chance
The SLYM owes its name to its position. Nestled between the arachnoid (middle membrane) and the pia mater (membrane closest to the brain), it means “lymphatic-like subarachnoid membrane“. Very thin, it is composed of only a few layers of cells and resembles the mesothelium, a thin protective tissue surrounding various organs such as the lungs or the heart. “SLYM cells share properties with the mesothelium, but they are probably not identical“, added Maiken Nedergaard, announcing having a kiss[…]
Read more on sciencesetavenir.fr