抄録
Eighteen cases of pleomorphic adenoma and three cases of adenoid cystic carcinoma were studied by electron microscopy, and the following results were obtained. 1) So-called neoplastic myoepithelial cells could be identified in pleomorphic adenoma and not in adenoid cystic carcinoma. These cells varied in morphologic nature of the intracytoplasmic filaments according to the pattern of the pleomorphic adenoma. 2) There were two kinds of epithelial mucin. One was the normal mucin which was a secretory product within ductal lumina, while the other was the abnormal mucin which was divided in to type I and type II. Type I of the abnormal mucin stayed mostly in the intercellular spaces of the parenchyma and had a tendency to flow out into stromal tissues. Type II was secreted directly from parenchymal cells to stromal tissues through the basement membrane. It was demonstrated that pleomorphic adenoma had both types of the abnormal mucin and adenoid cystic carcinoma had only type I. 3) It seemed to be natural to consider on the base of electron microscopic findings that the abnormal mucin had rather significant roles in formation of the myxoid and chondroid areas of pleomorphic adenoma and also in hyalinization of the cylindrical stroma of adenoid cystic carcinoma.
