Several special stains—hematoxylin and eosin (H&E), periodic acid–Schiff (PAS), Masson’s trichrome, Jones methenamine silver (JMS), and Congo red—are routinely used for histopathologic evaluation of renal biopsy specimens. Tissue sections should be thinner (2–3 microns thick instead of 5–6 microns thick) than those for other common histopathologic evaluations. This is particularly important when evaluating glomerular disorders, one of the most common reasons for renal biopsy.

A glomerulus from a dog with membranous glomerulonephropathy stained with H&E (A), PAS (B), JMS (C), and Masson’s trichrome (D). The glomerulus exhibits normal cellularity and moderate thickening of the capillary walls. The PAS and especially the JMS stains are particularly useful for assessing thickness of the glomerular basement membrane (GBM, black arrows). The JMS stain shows that the external (ie, subepithelial) surfaces of the GBM have irregular contours and small projections of GBM matrix (called spikes) extending outward (red arrow). The Masson’s trichrome stain shows red granules on the outer (ie, subepithelial) surfaces of the GBM that are deposits of immune complexes (arrowheads). Original magnification, 400×

(Figure 1A)

(Figure 1B)

(Figure 1C)