Observations on the Settling and Recoverability of Transplanted Hemopoietic Colony-forming Units in the Mouse spleen

A series of experiments was designed to study the effect of spleen size on the seeding and retention of spleen colony-forming units (CFU) after injection into irradiated mice. The cellularity of the spleens of recipient mice was varied using a variety of experimental procedures, and the resulting spleen colony production was analyzed with respect to CFU seeding. It was found that the major factor determining the seeding and ultimate retention of CFU in the spleen of a recipient mouse is the size of the spleen. It is concluded that the most reasonable value of the fraction of injected CFU that produces spleen colonies should be determined from the number of CFU recoverable from the fully shrunken spleen. In these mice, the fraction was 9.5%.