The cerebral cortex is the mantle of gray substance covering each half of the brain.
From the sciencedaily.com
Made with a gray substance similar to window caulking, it depicts a human figure struggling to stand up.
From the washingtonpost.com
A light-gray substance was sprayed across the tombstone in a southwestern suburb of the capital Nicosia, obscuring Papadopoulos'name and date of birth but leaving the tombstone otherwise unharmed.
From the abcnews.go.com
Brain scans of the living will show gray patches where a substance in the brain called myelin has died.
From the denverpost.com
Medial orbitofrontal cortex gray matter is reduced in abstinent substance-dependent individuals.
From the nature.com
They have devised a way to turn the brain's opaque gray matter into a glassy, see-through substance.
From the charlotteobserver.com
When I came to Baltimore, the Sun was a dour gray lady, but one of unquestioned substance, and there were two competing evening papers.
From the washingtonpost.com
While Earth's moon and other airless bodies are generally a relatively uniform gray, Vesta's bright background is streaked with large amounts of a much darker substance.