Figure 5: Histology of the thmus at 0, 4, and 21 days after intravenus injection of moth allergen extract (150 mg/kg) into albino mice. A = 0 days; B = 4 days; C = 21 days. Changes in the cortex are shown at a higher magnification. Cellular depletion at day 4 and increased proportions of mitotic figures indicated by an arrow at 21 days × 280