Introducing the brain: lymphatic fluid drainage (Introduction)

by David Turell , Wednesday, January 31, 2024, 16:48 (295 days ago) @ David Turell

In a plexus behind the nasopharynx:

https://www.sciencealert.com/discovery-points-to-a-sewage-system-for-the-brain-right-be...

"If the findings extend to humans, it could fundamentally change how scientists understand the circulation of fluid that bathes the brain and spinal cord.

"Cerebrospinal fluid (CSF) is a colorless liquid that carries nutrients to the central nervous system, maintains fluid balance, and clears away waste products from brain tissue.

"In humans, CSF is drained and replaced constantly, turning over three to five times a day. That clearance can slow with age, it is correlated with sleep quality and cognitive function.

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"CSF might not drain through the vascular system at all, but through the body's lymph nodes.

"A new study, led by researchers at South Korea's Institute for Basic Science and the University of Missouri in the United States, has identified a previously unknown thoroughfare that carries CSF from the brain to lymph nodes in the neck.

"According to the international team of researchers, a distinctive network of lymphatic vessels lies near the top part of the throat in mice, just behind their nose, that has never been clearly identified before.

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"In a review for Nature, University of Bern physiologists Irene Spera and Steven Proulx applaud the recent discovery. As authors of studies suggesting the possibility of such a 'secret passage', they say the results provide "indisputable evidence that, at least in mice, the nasopharyngeal lymphatic plexus has a crucial involvement in CNS clearance."

"'This plexus, beautifully rendered in three dimensions… is composed of a dense network of lymphatic vessels that wraps around the circumference of the nasopharynx," Spera and Proulx write.

"Even more promising, this lymphatic plexus is not just present in mice. Lead researchers Jin-Hui Yoon, Hokyung Jin, and Hae Jin Kim also examined the brains of crab-eating macaques and found a similar structure in the exact same spot.

"Although the team didn't get to see the vessels draining in action like they did in mice, the findings among primates suggest this pathway is conserved across diverse mammalian species.

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"Among humans, some recent evidence does suggest that CSF can drain into the nasal cavity at the top of the throat via cranial nerves.

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"'We plan to verify all the findings from the mice in primates, including monkeys and humans," says supervisor Gou Young Koh from the Institute for Basic Science.

Comment: the findings fit the fact that the lymphatic system drains fluids from all over the body. That this exists in mice and macaques strongly suggests humans have it. When evolution finds a working system it is conserved and appears in all related species.