Profound hyperplasia and increased rate of mucosal proliferation in CCR7^−/− mice. (A) In some CCR7-deficient mice the thickened fundic mucosa exhibited multiple diverticula (marked by arrows) beneath the muscularis mucosa or even in the subserosa. Diverticula penetrating the muscularis mucosa were also observed. Three representative examples are shown for mice older than 18 months. Magnification, ×100. HE staining in paraffin-embedded sections. (B) Analysis of cellular proliferation in gastric mucosa from wt controls and in CCR7^−/− mice. Determination of DNA synthesis rates was assessed by immunohistochemical detection of BrdU incorporation. Gastric mucosa from 10-week-old mice injected with BrdU was stained with anti-BrdU antibody (in red). Data are representative of 6 mice in each group. Original magnification, ×100 (left two panels); ×200 (right two panels). Hematoxylin counterstaining in paraffin-embedded sections.