Effects of fractionated irradiation on the esophageal mucosa: a scanning and transmission electron microscopic study.

The mucosa of rabbit esophagus was irradiated with daily fractions of 2 Gy to an accumulated dose of 20 Gy. Specimens were taken for scanning electron microscopy, transmission electron microscopy and light microscopy investigations. Examination was made 1-10 days after each fractionation schedule. Light microscopy showed dose-dependent edema of the irradiated mucosa which also could be seen and scored from SEM pictures. SEM investigations showed that this was accompanied by loosening of microridges and a slightly increased cell loss. By SEM, a varying amount of bacteria could be seen which did not make intimate contact with the surface cells. During the first five days there was a steady decrease of the number of bacteria in relation to the absorbed dose. In the later period of examination, the amount of bacteria increased up to a given dose of 10 Gy. Thereafter, the number faded off to about zero when 20 Gy had been administered.