Figure 1

Lung lesion from cattle naturally infected with M. bovis. (A–B) H&E (A) and Masson-Goldner’s Trichrome (B) staining of a typical tuberculous classical granuloma lesion (white arrow) with central mineralization and peripheral fibrous capsule surrounded by satellites smaller lesions (black arrows). *: caseous necrosis, #: fibrous capsule. C, D Higher magnification of A and B showing an intact neutrophil area (“N” & Zoom) below the fibrous capsule (#) interspersed by foamy and epitheliod macrophages (“M”). E, F H&E (E) and Masson-Goldner’s Trichrome (F) staining of extended lesion with abundant caseous necrosis and karyorrhectic debris areas (“K”) but low discontinuous fibrous capsule (#), representative of an invasive necrotizing granuloma. G, H Higher magnification of E&F showing an example of a satellite aggregate of necrotic neutrophil (“N”, zoomed in (H)) next to the karyorrhectic debris (“K”) and caseous necrotic rich area (*). I High magnification of a foamy macrophages and epitheliod cell dense area containing multinucleated Langhans giant cells (black arrows). J Ziehl staining, high magnification of a central necrotic area showing extracellular bacilli within cellular debris. Scale bars: 25 μm (D-Zoom & H-Zoom); 50 μm (I and J); 100 μm (C, G, D, H); 200 μm (A, B, E).