To investigate the transformation pattern of macrophage in granulomatous lesions, methylcelluolse was injected into the subcutaneous layer of the rats and the tissues reacted to the methylcelluose was examined light and electron microscopically 3rd days, 1st, 2nd, 4th, 8th, and 12th week apher the methycellulose injection.
The following results were obtained
1. Macrophages had many round vacuoles in the cytoplasm. They tended to fuse with each other and made large vacuoles. The macrophages were mixed with epitheloid cells which had scanty vacuoles. Multinucleated giant cells contained an abundance of large vacuoles.
2. Ultrastructurally, the macrophages usually were separated and had abundant vacuoles and scant cytoplasm. The vacuoles in the 3rd day and 1st week of experiment were relatively small, round and were gradually fused consequently making variable vacuoles of irregular size and shape. In the cytoplasm of multinucleated giant cells, the vacuoles were changed to a cyst-like giant vacuole. In the forci aggregation of machrophages, each cell was interdigitated by abundant cytoplasmic processes, and it had tended to fuse with indistinct cytoplasmic membranes. Multinuclated giant cells had an abundance of cytoplasm, cystic vacuoles and interdigition in a part of their cytoplasm.
These results suggest that macrophage is transformed to multinucleated giant cells via fusion of intercellular digitation, epithelioid cells and multinucleated giant cells may be adapted to secretory or digestive function rather than phagocytosis.
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