Dose-response studies of single dose ionizing radiation on the ciliated epithelium of the trachea of the rabbit. A physiologic and ultrastructural investigation.

The effects of ionizing radiation on the ciliated epithelium of the rabbit's trachea were studied by ultrastructural and physiologic examinations during 10 days after single doses of 2 to 30 Gy. Low doses (2 and 2.5 Gy) caused during the first days after irradiation increased ciliary activity which during the following days returned to normal. Ultrastructurally blebs were observed on the cilia. Five and 10 Gy caused slight increment of the ciliary activity, also more marked structural effects with swollen ciliary tips, bent tips and some cilia broken and adhering to each other. Larger single doses (15-30 Gy) caused reduced and irregular ciliary activity; ultrastructurally, most cilia were broken and adhered to each other, but some cilia seemed to be unaffected. The goblet cells increased in number already after 2 and 2.5 Gy. Mucinous granula could be observed on the ciliary surface and after 30 Gy there was an explosive emptying of the goblet cells.