Fig. 6.

Histological presentations of subclinical chronic systemic inflammation-associated lesions seen in C57BL/6 mice aged 16–36 months. A. Hyperplastic mesenteric milky spot. B. Higher magnification of A. The reactive milky spot contains large and small lymphocytes, plasma cells, and Mott cells (arrows). C. Low magnification overview of chronic renal lesions. Interstitial lymphoid aggregates (*) and tubular ectasia (arrow) with degeneration, regeneration, necrosis and membranous glomerulonephropathy. D. Thickened mesangial matrix (*) and periglomerular fibrosis (arrow) characterize membranous glomerulonephropathy. Glomerular amyloidosis should also be considered. PAS and Congo Red histochemical stains can aid in differentiation. E. Chronic adenitis occurs in numerous glands including the exorbital lacrimal gland. F. Higher magnification of E. Lymphoplasmacytic inflammation disrupts the gland architecture. Note ectatic duct (*). G. Amyloid accumulation in the small intestinal villi. H. Higher magnification of G. An accumulation of light pink homogenous extracellular material (amyloid) in the lamina propria widens the villi. I. Cross-section of the base of the tongue with poly arteritis nodosa (box and *). Lingual minor salivary glands are indicated (arrow). J. Movat's pentachrome staining of lingual artery in I. The affected segment (*) lacks in elastic lamina (thin black line) and the media is expanded by smooth muscle cells. Mild to moderate perivascular chronic inflammatory cells (arrow) and lumena (L) are indicated. Similar necroproliferative arteritis near the inner and middle ear may result in neurological signs (see text for details). K. Low power view of lung severely affected by AMP. L. Higher magnification of AMP demonstrates the intrahistiocytic crystalline material (*) and dense perivascular and peribronchiolar lymphoplasmacytic inflammation, which is frequently present in severe cases. Hemosiderophage (arrow) and hyalinized respiratory epithelium (arrowheads) are indicated.