Loss of crypts is coincident with the onset of diarrhea, dehydration and mortality. The top plots illustrate the number of C57BL/6 mice per radiation dose (y axis) exhibiting diarrhea of a score 1 (mild) or 2 (severe) from days 3 to 7 (am and pm observations indicated by DA3, DP3, DA4, DP4 etc). The lower plots illustrate the same data in CBA/Ca mice, where the diarrhea occurs slightly earlier than the C57BL/6 mice. Grey bars indicate the number of animals remaining in the study.