EFFECT OF RADIATION ON GROWTH OF VERTEBRAE IN TAILS OF RATS .2. SPLIT DOSES OF X-RAYS AND EFFECT OF OXYGEN

Vertebrae in the tails of rats have been irradiated with single and split doses of x-rays under reduced, normal and increased conditions of oxygenation. Split doses were less effective in stunting vertebral growth than single doses. This sparing effect was dependent on the time between fractions and the size of the total dose, but independent of vertebral oxygenation. These results are accounted for in terms of the recovery of epiphyseal cartilage cells from sublethal injury. It is suggested that with x-rays the survival curve for epiphyseal cells in situ has a large shoulder followed by an exponential part. © 1969 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.