CSF-Carrying Meningeal Lymphatics Found Running Along Dural Sinuses

Here's another cause for textbook revision in the works. I wonder how far into the pia these lymphatics run in humans? Are they periventricular at all? Perhaps some forms of communicating hydrocephalus will turn out to be a lymphatic drainage disorder.

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ABSTRACT

Structural and functional features of central nervous system lymphatic vessels

Antoine Louveau, Igor Smirnov, Timothy J. Keyes, Jacob D. Eccles, Sherin J. Rouhani, J. David Peske, Noel C. Derecki, David Castle, James W. Mandell, Kevin S. Lee, Tajie H. Harris & Jonathan Kipnis

Nature (2015) doi:10.1038/nature14432

Received 30 October 2014 Accepted 20 March 2015 Published online 01 June 2015

One of the characteristics of the central nervous system is the lack of a classical lymphatic drainage system. Although it is now accepted that the central nervous system undergoes constant immune surveillance that takes place within the meningeal compartment1, 2, 3, the mechanisms governing the entrance and exit of immune cells from the central nervous system remain poorly understood4, 5, 6. In searching for T-cell gateways into and out of the meninges, we discovered functional lymphatic vessels lining the dural sinuses. These structures express all of the molecular hallmarks of lymphatic endothelial cells, are able to carry both fluid and immune cells from the cerebrospinal fluid, and are connected to the deep cervical lymph nodes. The unique location of these vessels may have impeded their discovery to date, thereby contributing to the long-held concept of the absence of lymphatic vasculature in the central nervous system. The discovery of the central nervous system lymphatic system may call for a reassessment of basic assumptions in neuroimmunology and sheds new light on the aetiology of neuroinflammatory and neurodegenerative diseases associated with immune system dysfunction.

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