Scanning electron, light, and immunofluorescent microscopy of intestine of gnotobiotic calf infected with calf diarrheal coronavirus.

Intestinal lesions in 2 gnotobiotic calves given (oral inoculation) calf diarrheal coronavirus were studied by scanning electron, light, and immunofluorescent microscopy. The calves were euthanatized at 34 and 73 hours after the onset of diarrhea. Lesions in the small intestine were similar to those reported in animals affected with transmissible gastroenteritis of swine. Small intestinal villi were shortened, some adjacent villi were fused, and villous epithelium was composed of low cuboidal to squamous cells. In the ansa spiralis coli, there were atrophy of the colonic ridges and marked differences in length and spacing of the microvilli on individual epithelial cells.