Morphology of Pulmonary Vasoconstriction and Vasodilation

Abstract

Pathology is the study of deviations from the norm in the morphology of organs, tissues or cells. However, not all deviations of what is generally considered the norm, are necessarily pathologic. As far as the pulmonary vasculature is concerned, this applies particularly to the result of functional alterations such as constriction or dilation. It is often believed that the morphological expression of these functional changes will disappear immediately following death of the tissue, so as to become unrecognizable for the pathologist. Generally this is not true. When lung tissue is fixed in the proper way immediately after becoming available, prominent vasoconstriction and vasodilation can be identified by light and electron microscopic study. The effect is usually abolished only when there is distinct autolysis of the tissue. For this reason, lung tissue obtained at autopsy is generally unsuitable or at least not very reliable for this purpose. Therefore, most studies in which constriction and dilation of lung vessels could be demonstrated, were based upon lung biopsy material or experimental work.