The effects of fractionated megavoltage X-irradiation on the rat submandibular gland: an assessment by light microscopy and autoradiography.

Abstract— Twenty‐four rats were divided into groups that received cumulative dosages of 500, 750 and 1000 rads of fractionated megavoltage X‐irradiation. Animals sacrificed three days post‐irradiation showed marked acinar atrophy but no vascular or ductal changes and isolated areas exhibited more severe damage, predominately vacuolation, apoptosis and total cell destruction. The severity of the changes mirrored the total cumulative dosage. Animals sacrificed 14 days post‐irradiation showed a marked return to pre‐irradiation morphological status. Greater recovery was noted in the 1000 rads dose than in the lower dose groups. A marked increase in vascularity reflected the recovery process. Auto‐radiographic estimations using (H) leucine supported the morphological changes only in the 1000 rad groups and these showed the least uptake at three days, but by 14 days exhibited the greatest increase—far above the level of control animals. Apoptosis apparently enables the tissues following repair of reversible damage to return to normal cellular activity. 1985 Australian Dental Association