Endothelial cilia in human aortic atherosclerotic lesions.

"Primary" cilia were present in the endothelial cells of human aortic fatty dots and streaks but not in those of normal intima. They had the features of cilia of the "9 + 0" axonemal configuration observed in many other cells. A lateral foot process and transitional fibers "anchored" the ciliary basal body in the cytoplasm, but rootlets were not identified in material examine. Ladder-like configurations interconnected the two centrioles (= diplosome) of control endothelium. The "primary" cilia of endothelium differed from those of the rudimentary type observed in smooth muscle cells in similar lesions of man, but shared many features with cilia of those present in experimental atherosclerosis in rabbit. Cilia were rarely described in vascular endothelium. It is believed that, to date, they were not reported to occur in normal or pathological arteries in man. It is being stressed that whereas the significance of these unusual organelles remains uncertain, their widespread occurrence may indicate that their role is more important than was believed previously, and they should cease being a curiosity only.