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:
“The high that proved too high, the heroic for earth too hard,
The passion that left the ground to lose itself in the sky,
Are music sent up to God by the lover and the bard;
Enough that he heard it once; we shall hear it by and by.”
—Robert Browning (1812–1889)
“What is a country without rabbits and partridges? They are among the most simple and indigenous animal products; ancient and venerable families known to antiquity as to modern times; of the very hue and substance of Nature, nearest allied to leaves and to the ground,—and to one another; it is either winged or it is legged. It is hardly as if you had seen a wild creature when a rabbit or a partridge bursts away, only a natural one, as much to be expected as rustling leaves.”
—Henry David Thoreau (1817–1862)