[The pathogenesis of the experimentally induced cholesterol granuloma (author's transl)].

Histochemical and polarizing microscopic studies were carried out in the experimentally induced cholesterol granuloma following mechanically blocking the eustachian tube of squirrel monkeys. Cholesterol granuloma was found in the long-term animals. Granulation tissues containing cholesterol crystals possessed various oxidative and hydrolytic enzymes except alkaline phosphatase. The shape and size of the cholesterol crystals were variable depending on the surrounding substances. In the middle ear fluid, the crystals showed large rectangular structures. However, they had a tendency to be smaller and thinner, as the collagen fibers were richer in the granuloma. The cholesterol crystals might be dissolved by a phagocytotic function of granulation tissue cells in the healing process of the granuloma.