Glymphatic system? How is the word glymphatic composed?

Well, obviously "g + lymphatic." But what g refers to here?

Context:

Sleep: The Ultimate Brainwasher?

...

The new work, published online today in Science, “fits with a long-standing view that sleep is for recovery—that something is paid back or cleaned out,” says David Dinges, a sleep researcher at the University of Pennsylvania. It builds on Nedergaard's recent discovery, described last summer in Science Translational Medicine, of a network of microscopic, fluid-filled channels that clears toxins from the brain, much as the lymphatic system clears out metabolic waste products from the rest of the body. Instead of carrying lymph, this system transports waste-laden cerebrospinal fluid (CSF). Before the discovery of this "glymphatic system," as Nedergaard has dubbed it, the brain's only known method for disposing of cellular trash was to break down and recycle it within individual cells, she says.

More:
http://news.sciencemag.org/brain-behavior/2013/10/sleep-ultimate-brainwasher