The microscopic examination of jejunum in affected calves compared with the healthy jejunum. (A) Hematoxylin- and eosin-stained sections of jejunum from the healthy calves. Images were obtained on an Olympus BX-50 light microscope at 5-fold original magnifications. The jejunum of the healthy calves showed normal epithelial cell in mucosa and submucosa. (B) The microscopic lesions of jejunum tissues collected from affected calves showed intestinal capillary congestion (arrow a), cell necrosis in smooth muscle (arrow b) and exfoliation of epithelial cells in mucosa (arrow c).