To determine the dose-survival and repair characteristics of the jejunal crypt cells, experimental study was carried out using total 70 mice.
Single or split irradiations of 1100 to 2200 rad were delivered to whole bodies of C_(57) BL mice, using a cesium 137 animal irradiator and those mice were sacrificed after 90 hours.
The number of regenerating crypts per jejunal circumference was counted, by a jejunal crypt cell assay technique, and dose-response curve was measured. The results were as follows:
1. The average number of jejunal crypts per circumference in control group was 140.
In a single irradiation group, the number of regenerated jejunal crypts was 125, 56, 2 in each subgroup of 1100 rad, 1400 rad and 1800 rad respectively.
In split irradiation´ group, it was 105, 44, 2 in each subgroup of 1400 rad, 1800 rad and 2200 rad respectively.
2. Mean lethal dose of mouse jejunal crypt cell was 167 and 169 rad respectively in a single and split irradiation.
3. Repair dose of sublethal damage was 280 rad.
4. Sublethal damage was completely repaired within 4 hours between the split dose of irradiation.
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