Immunohistochemistry for Mmm in CBPP naturally affected cattle. A specific, dendritic-like IR was observed in newly-formed lymphoid follicles, located within the wall of a sequestrum (A). The Mmm-IR was also detected along/inside the bronchiolar (B) and alveolar (C) epithelial cells, as well as along the endothelial surface of a blood vessel (D). Mayer’s hematoxylin counterstain. Scale bar: 10 µm (C), 20 µm (B), 50 µm (A, D).