In connective tissue, ground substance is the non-cellular components of extracellular matrix which contain the fibers.
It is usually not visible on slides, because it is removed during the preparation process.
Cells are surrounded by extracellular matrix in tissues, which acts as a support for the cells. Ground substance traditionally does not include collagen but does include all the other proteinaceous components, including proteoglycans, matrix proteins and, most prevalent, water. The non-collagenous components of extracellular matrix will vary depending on the tissue in which it is found.
Ground substance is amorphous, gel-like, and is primarily composed of glycosaminoglycans (most notably hyaluronan), proteoglycans, and glycoproteins.
The meaning of the term has evolved over time.
Famous quotes containing the words ground and/or substance:
“If there were one who lived wholly without the use of money, the State itself would hesitate to demand it of him. But the rich man—not to make any invidious comparison—is always sold to the institution which makes him rich.... Thus his moral ground is taken from under his feet.”
—Henry David Thoreau (1817–1862)
“Ah, to build, to build!
That is the noblest art of all the arts.
Painting and sculpture are but images,
Are merely shadows cast by outward things
On stone or canvas, having in themselves
No separate existence. Architecture,
Existing in itself, and not in seeming
A something it is not, surpasses them
As substance shadow.”
—Henry Wadsworth Longfellow (1807–1882)