Electron microscopic study of aberrant lipogenesis in the cornea

Aberrant lipogenesis is a protective reaction of cells by synthesis of triglycerides utilizing abnormally present oleic acid. In order to elucidate cytologic details of this phenomenon, a small amount of sodium oleate was injected into the corneal stroma of the rabbit, and the fat-forming cells were examined by electron microscopy. When tritiated oleate was used, the cytoplasm of the stroma cells in the vicinity of the injection site became diffusely radioactive immediately following the injection. The radioactivity was gradually concentrated in fat droplets. The cytoplasm of the corneal stroma, which contains relatively sparse micro-organelles, began to form small, slightly electron-dense spaces measuring 300-1000 A in diameter in the matrix, without correlation to any micro-organelle. These spaces never became radioactive. They may be the site of glyceride formation. These spaces became membrane-bound oil droplets measuring 500-100 A in diameter within 6 hours. The number and size of oil droplets increased for a few days and remained intracellular for a long period of time without causing any degenerative effect to the cell. The fatty substance had been proven to be mainly triglycerides in the earlier studies. Some longstanding fat droplets developed a few myelin figures. These lamellar membranes were heavily incorporated with the radioactive oleate.