The morphological changes and proliferative activity of FRTL-5 cells i
rradiated in vitro with one dose of 0, 8, 12, 16, 24 or 32 Gy were stu
died morphometrically 7, 14 and 21 days after irradiation. The number
of cells irradiated with 24 Gy and 32 Gy decreased during the 3 weeks
of the experiment. Morphometrical analysis confirmed that the cells re
paired their injuries up to 16 Gy of irradiation, while doses of 24 an
d 32 Gy damaged them irreversibly. Thyroglobulin was detected in cells
after all doses of irradiation.