The effects of 10 Gy single-dose irradiation on the ciliated epithelium measured during and one-to-ten days following irradiation. A comparative physiological and morphological study.

Experiments recently done in this laboratory have shown that ionizing irradiation can result in an increase in the ciliary beat frequency of the trachea in vitro even during ongoing irradiation, implying an immediate stimulation of the physiological activity of the cells. This phenomenon is not fully understood and is by itself contradictory to general radio-biological concepts. Ultrastructural investigations on specimens taken immediately after irradiation (10 Gy) have, so far, not shown any changes. It has therefore seemed useful to extend the investigations by examining the effects of in vivo- irradiation (10 Gy) on rabbit trachea during the first 10 days after treatment. The following results have been obtained: Phase I: On days 1-3 after irradiation the beat frequency showed a slight increase (10%) within the irradiated part in comparison with a non-irradiated area of the trachea. No pronounced ultrastructural changes were found these days. Phase II: On days 4-7 after irradiation the mucociliary activity was reduced in those places where it could be measured. The surface of the cilia assumed a generally destructed appearance with elongated cilia and disorganisation. TEM-pictures showed an increased amount of goblet cells and signs of membrane damage such as cytoplasmic extrusions at the apical end of the cells. Phase III: On days 8-10 after irradiation a normalization of the tissue gradually took place with a beat frequency returning to normal. The ciliary surface showed a recovery process which also could be observed in the TEM-pictures.