["Ghost" bodies and calcification in experimental coronary artery atherosclerosis in pigeons]

Nineteen young pigeons (columba livia domestica) fed on cholesterol (0.5 g per day per bird) for 31 weeks were studied by electron microscopy focusing on calcification in coronary artery atherosclerosis. After 24-31 weeks of cholesterol feeding, smooth muscle cells (SMCs) in the media layer showed an obvious proliferation. Many of these cells had bulbous cytoplasmic pseudopod-like processes connecting with the cell body by narrow stalks. Many of the cytoplasmic pseudopodia as well as the detached cell fragments, i.e. "ghost" bodies measuring 606-2235 nm in diameter were membrane-bounded, but without basement membrane, often with a fibrillo-granular content and occasionally seen as residue of organelles of the SMCs. Additionally, in the interstitial spaces, much vesicle-like deeply osmiophilic material was obtained, suggesting degradation products of SMCs. Furthermore, in the matrix, there were many calcium spherules measuring 551-3006 nm in diameter, consisted of 1-3 layers of radiating crystalline spicules. The mechanism of formation of "ghost" bodies and calcification is discussed.