General Properties of Endothelial Cells

Abstract

This session deals predominantly with endothelium, and is to be introduced by observations on the general properties of endothelial cells. Of course, we first have to consider the question whether general properties of the vascular endothelium can be said to exist at all. Considering the endothelium from the light microscopic point of view only, there is indeed a generally accepted definition that “the endothelium provides the lining of the blood vessels, heart chambers and lymphatic vessels by forming a single layer of cells”. But under the electron microscope endothelial cells show structural differences which depend upon their location in the vascular system. These ultra-structural pecularities of the endothelium led to a classification of endothelial cells into different morphological types. Further investigations considering both the morphological and functional aspects of this tissue revealed, however, that transformations between the different types of endothelial cells can occur. These observations indicate that the vascular endothelium should be regarded as a dynamic structure. The overall distribution of the endothelium within the body suggests that we are dealing with the most frequently occurring type of mammalian cell, and one which also plays a predominant role with regard to number and weight.