SURGERY WITH SPECIAL REFERENCE TO PODIATRY - Edward Adams - Bog

Every tissue is composed of two parts: the cellular elements and
the intercellular substance. These are called cells and stroma. Upon the
first of these depends the vitality and function of the part, while its
density, shape and general physical properties are determined by
the second. Likewise along the same lines of reason, all of our
organs have two separate areas of tissue: theparenchymatous and
the interstitial. The first contains the functioning and the second the
supporting elements.
The physical conditions of the interstitial tissue or the intercellular
substance vary greatly in density. Blood is a tissue, the intercellular
constituent of which is fluid, and as we consider more dense tissues,
we encounter all degrees of density of the framework or
intercellular substance, until with the additional presence of
calcareous elements, we conceive the hardness of bone and dentine.
Tissues as a whole, however, are not solid; there are spaces in the
supporting structure to admit of the passage of arteries, veins,
nerves, and lymphatics.
Abnormal conditions arise in the various parts of the tissues. Certain
diseases affect the parenchymatous tissue in an organ more than the
interstitial tissue and again others affect the blood vessels
particularly.