Dermal endothelial cells, fluorescence light micrograph. This tissue (from the skin) is endothelial, from the inner surface of blood vessels. The tissue is described as microvascular in nature. The cells have been stained for CD31 (PECAM-1, green), a protein found here at endothelial cell intercellular junctions. The cells have also been stained with von Willebrand Factor (vWF, red) and the cell nuclei have been stained blue. This sample is from human tissue.