RADIATION-INDUCED CELL-PROLIFERATION IN THE PAROTID AND SUBMANDIBULARGLANDS OF THE RAT

Repopulation of tissues with cells at damaged sites is an important fe ature in the recovery of radiation-induced tissue injury. To obtain in sight into the regenerative process in salivary gland tissue, prolifer ative activity was measured as a function of time in the different epi thelial cell compartments of rat parotid and submandibular glands afte r local X irradiation with a single dose of 15 Gy. Bromodeoxyuridine-l abeling indices were determined before and 10 h and 1, 3, 6, 10, 15, 2 0 and 30 days after irradiation. In both glands, X irradiation caused cell death and cell cycle delay manifested during the first day. Three days after irradiation, cell proliferation started in the intercalate d duct. Six days after irradiation, proliferation was also observed in acinar and granular convoluted tubule cells. The striated ducts showe d proliferative activity starting at day 6 (parotid) and day 10 (subma ndibular), respectively. The results of this study suggest that after 15 Gy of X rays repopulation takes place in all cell compartments. Fro m the present study it cannot deduced if these cells are originating s olely from progenitor cells residing in the intercalated duct or if ce lls of the other compartments are also stimulated. Proliferative activ ity was found to be higher in the intercalated duct compartment of the parotid gland than of the submandibular gland, which may be related t o the suggested greater radiosensitivity and thus a greater demand for cell replenishment in the parotid gland.