The spleen colony technique. III. Comparison of the overlap effect and of errors in CFU-s determination and the [3H]-thymidine suicide data for several strains of mice.

A mathematical model of errors of the spleen colony technique is applied to data obtained from four mouse strains and F1 hybrids. The variance of the colony counts was close to the Poisson distribution in inbred mice and F1 hybrids. However, it should be checked regularly. The magnitude of the error in CFU-s determination and of the estimations of the S phase fraction was derived, and is presented relative to the mean colony counts for all mouse strains studied. The optimum spleen colony counts are generally higher than those which are commonly used. However, the utilization of the optimum spleen colony counts requires a correction for the effect of colony overlap.