Reduced thymus size found in born AML1Δ446/Δ446 mice. (A) Macroscopic appearance of the dissected thymus from representative litters resulting from intercrossing of mutant mice heterozygous for either full-length cDNA knock-in (+/WT) or Δ446 mutant knock-in (+/Δ446) at the age of 4 days, 5 weeks, and 15 weeks. M indicates homozygous mutants. (B) Columns with bars for standard deviation indicate the number of cells per one lobe of thymus from littermate mice of each genotype. Numbers of mice examined are indicated in parentheses at the bottom. Statistically significant differences are shown as P values. (C) Microscopic appearance of hematoxylin-eosin–stained sections of the thymus are illustrated in the top panels (original magnification, × 13.2), and results of flow cytometric analysis of the CD4 and CD8 expression for thymocytes and splenic T cells are shown below.
