Biological complexity: how eyes get cleaned (Introduction)

by David Turell , Monday, April 27, 2020, 23:12 (1453 days ago) @ David Turell

Turns out same way as the brain with a very specialized system:

https://medicalxpress.com/news/2020-04-discovery-scientists-eyes-cellular-debris.html

"Like the brain, the eyes lack the classic lymphatic vessels responsible for the circulation of fluids and removal of waste products, as is common in peripheral organs. In recent years, it was discovered that the brain possesses a unique "glymphatic" system, a privileged brain-only method of draining and disposing of molecular wastes. This transport system, when healthy, involves shuttling neurotoxic proteins such as amyloid-β out of the brain.

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"The new findings explain how a glymphatic system maintains eye health and underscores that impairment—clogging—of this vital waste pathway can lead to glaucoma, a major worldwide cause of blindness. Nedergaard has defined "glymphatic" as an amalgam of the words glial and lymphatic. Glial cells are the primary cellular components that support neurons—nerve cells. The glymphatic pathway substitutes for a lymphatic system, which exists in neither the brain nor the eye.

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"Intriguingly, the team found the lymphatic vessels are connected to the same pathways that dispose wastes from the brain. The discovery is a scientific first and opens a new window into understanding how the eyes clear metabolic and cellular debris. The findings also shed new light on how the eyes and brain share critical pathways.

"Even though the finding is new, the waste clearance system in the brain was first defined by Nedergaard in 2012. The pathway involves a labyrinth of intricate perivascular tunnels that are formed by glial cells, which underlie the efficient elimination of soluble metabolites from the central nervous system. In addition to waste disposal, Nedergaard and colleagues also have found that the pathways support the distribution of critical nutrients and compounds throughout the brain, substances that include glucose, amino acids, growth factors and lipids."

Comment: Another highly complex system that has to be designed.