Injury and Repair following Irradiation of Salivary Glands in Male Rats

Abstract

1. The weights, histology, histochemistry and mitotic indices of salivary glands in male rats were analysed and the long term effects of local irradiation on the main components of the parotid, sublingual and submandibular studied. 2. The excretory ducts are least and the acini are most affected by radiation while the intercalated ducts and the submandibular secretory tubules are intermediate. An initial period of predominantly degenerative changes is followed by a phase of regeneration and abnormal repair which leads to the appearance of adenomas in the sublingual and submandibular but not in the parotid. 3. In the parotid acini only show regenerative activity and repair the injury caused by low, but not by high doses of radiation. In the submandibular and sublingual partial and unsuccessful regeneration of acini follows radiation injury and elicits excessive proliferation of intercalated ducts which leads to the formation of adenomas. 4. Irradiation produces changes in the type, amount and direction of discharge of the secretion and in the polarity of cells of sublingual and submandibular acini. 5. The intercalated ducts of the parotid lose their cytoplasmic granules while those of the sublingual are stimulated to form mucin. The activity of the secretory tubules of the submandibular appears to be relatively increased by radiation. 6. The relation of the radiosensitivity of the various glandular components to their mitotic and functional activities and to their regeneration pattern is discussed.