Histopathology of tissue samples collected from a captive European bison (Bison bonasus) infected with Mycobacterium bovis.
A Mesenteric lymph node showing multiple and confluent granulomatous inflammation with caseous necrosis and central mineralization pushing the lymph node tissues against its capsule. Haematoxylin and eosin stain. B Lung tissue with foci of granulomatous inflammation characterized by central necrosis surrounded by epithelioid macrophages. Lymphocytes, plasmocytes and occasionally well-differentiated fibroblasts were observed delimiting the granuloma. Haematoxylin and eosin stain. C Histochemistry of a section from the lung granuloma showing a great number of acid-alcohol resistant -alcohol resistant bacilli (BAAR) consistent with Mycobacterium spp. Ziehl–Neelsen stain