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.