Thymic and lymph node atrophy in Apc^Min/+ mice. (A) Thymi from (i) wt and (ii-iii) Apc^Min/+ animals at 100 days of age showing the reduction in size and variable rate of atrophy in Apc^Min/+ mice. (B) Thymic histology of (i) wt thymus and (ii-iv) Apc^Min/+ thymi at 100 days of age. Three different thymi from the same age Apc^Min/+ animals are shown demonstrating the initial depletion of cortical thymocytes and the variable rate and stages of atrophy. The most advanced stage of atrophy is shown in panel iv. Sections are stained with H and E. X indicates cortex; and M, medulla. (C) Lymph node histology of (i) wt and (ii-iv) Apc^Min/+ lymph nodes at 100 days of age. Inguinal lymph nodes from 3 different Apc^Min/+ animals at various stages of atrophy are shown demonstrating the progressive depletion of the paracortex. Sections are stained with Giemsa. PX indicates paracortex; PF, primary follicle; and GC, germinal center. Original magnification, × 10 (A); × 200 (B-C).