This section from huma skin shows a capillary in a dermal papilla cut in longitudinal
section. The nuclei of the endothelial
cells that form the wall of this vessel are elongated, flattened and
bulge into the lumen. They are also oriented such that their long axis is
parallel with the long axis of the capillary. The elongated nucleus that bulges
not into the lumen but into the connective tissue is a perivascular
cell (pericyte), which serves as a precursor to new endothelial cells.
Although not apparent, capillaries have a thin covering of collagen fibers
derived from the surrounding connective tissue.
