Cell-Survival Characteristics of Intestinal Stem Cells and Crypts of γ-Irradiated Mice

Ninety-one female Swiss Webster mice which survived to 4 days after whole-body irradiation (/sup 137/Cs-..gamma.. rays, 102 rad/min) were sacrificed for assay of the number of surviving crypts. (/sup 3/H)Thymidine was injected 45 min prior to sacrifice and crypt survival determined from /sup 3/H counts per crypt, /sup 3/H counts per milligram of dry intestine, and the dry weight of the whole intestine after single doses of 960 to 1924 rad or split doses (4-hr interval) of 1155 + 385 to 962 rad. For the two highest doses in each series, for which crypts were very sparse, the /sup 3/H-counting procedure was replaced by a visual count in a specimen large enough to be weighed. The results were analyzed using, for comparison, various mathematical models. The best fit was obtained with nonlinear regression using a multitarget-with-two-components model. The parameters of this curve are D/sub 0/, 109 rad; n (cell extrapolation number), 55; and A (stem cells per crypt), 31. The results are compared with those obtained by other workers.