Fig. 1

Histopathological changes in the ileal mucosa. a, b Histological features in the infection groups are shown with hematoxylin and eosin staining at 5 dpi and 12 dpi. Degeneration, dissolution and necrosis of the mucosal epithelial cells are indicated with the black arrow. Loose of the connective tissue is indicated with the yellow arrow. Pyknosis and atrophy of the intestinal glands are indicated with the red arrow. c, d Histological features in the control groups are shown with hematoxylin and eosin staining at 5 dpi and 12 dpi; e Measure of villus length by Image pro-plus, version 6.0 (Control = 5, Infection = 5). f Measure of crypt depth by Image pro-plus, version 6.0 (Control = 5, Infection = 5). g Spatial distribution of villus-length/crypt-depth of Control and Infection groups. ** p < 0.01