[Individual variability in the number of stem cells in mammalian tissues]

The distribution of animal groups (3--4 control or gamma-irradiated mice per group) were obtained when analysing published data on the mean number of the CFUs in the femoral bone marrow or stem cells of small intestinal crypt. Almost 50% of such groups have the mean number less than the geometric mean. The mean value for the group of animals deviation from the expected geometric mean for all animal population for more than 2.5 times, both for the larger values and for the smaller, was about 5% in such groups for the marrow CFUs and 20% for intestinal stem cells. The percentage of mice, that died from acute radiation sickness after acute irradiation, was related with the parameter D(0), that characterized the CFUs survivability on the exponential part of the survivability curve. The negative correlation (r = -0.83) was determined between the mean value of the small intestine crypt stem cells and the ability of intestinal stem cells to the radiation damage reparation, evaluated through the parameter D(q) of the stem enterocyte survival curve for this animal groups.