Gastric antral epithelial cell proliferation. Ki67 staining of the antrum of a gerbil inoculated with H. heilmannii s.s. ASB1 (b) showing a higher number of proliferating epithelial cells compared to a sham-inoculated negative control animal (a). The rate of epithelial cell proliferation was determined by counting Ki67-positive epithelial cells in 5 randomly chosen High Power Fields at the level of the gastric pits (magnification: 400×) in the antrum of the gerbil stomach (c). The mean numbers of Ki67-positive cells are shown in each experimental group. Significant differences between H. heilmannii s.s.-inoculated and control animals are indicated by * (ANOVA, p < 0.05). Significant differences in comparison with ASB7 and ASB9 inoculated groups are indicated by + and # respectively (ANOVA, p < 0.05).