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:
“Even great towers start at ground level.”
—Chinese proverb.
“But they that hold God to be [an incorporeal substance] ... do absolutely make God to be nothing at all. But how? Were they atheists? No. For though by ignorance of the consequence they said that which was equivalent to atheism, yet in their hearts they thought God a substance ... So that this atheism by consequence is a very easy thing to be fallen into, even by the most godly men of the church.”
—Thomas Hobbes (1588–1679)