The Induction of Adenomas by the Irradiation of Salivary Glands of Rats

Abstract

Local irradiation induces adenomas in the three major salivary glands of rats. Their incidence varies with dose, over-all time of treatment, and sex of the animals. The sublingual gland is most and the parotid the least prone to adenoma formation; the submandibular gland is intermediate. With fractionated protracted doses of x rays the tumor formation is greater than with concentrated smaller doses in the parotid, the submandibular, and the skin, but lower in the sublingunal. For the same dose of x rays the sublingual produces 100% adenomas in males and 50% in females, but none in castrated females. Adenomae occur only in regions in which the acini have disappeared. They are of acinar type in the sublingual and submandibular, formed by the proliferative activity of intercalated ducts. In the parotid they are of tubular type and formed by dedifferentiated ducts. Radiation causes compensatory secretory activity in the intercalated ducts of the sublingunal and the tubules of the submandibular gland but the disappearance of secretory granules in the intercalated ducts of the parotid. Adenoma formation follows the stimulation of regenerative activity in intercalated ducts and in the parotid of excretory ducts by the progressive disappearance of acini and the compensatory activitymore » of the secretory tubules. It is influenced by the sex of the rats and by the type of radiation treatment, but is not a function of radiation dose.« less