Effect of the Slt mutant allele on the production of tissue mast cells in mice.

The effect of the Slt mutant gene on the production of melanocytes, tissue mast cells, and erythrocytes was compared with the effect of the Sl and Sld mutant genes on the same genetic background [(WB X C57BL/6)F1 mice]. Although the rank order of cell numbers was similar in these three types of cells (i.e., +/+ greater than Slt/Slt greater than Sld/Slt greater than Sl/Slt greater than Sl/Sld), the difference in the melanocytes was largest, and the difference in the erythrocytes was smallest. Since male Slt/Slt mice (on both WB and C57BL/6 backgrounds) were fertile, such mice were useful for efficient production of moderately mast-cell-deficient Sl/Slt and Sld/Slt mice.