Figure 1.

Commonly used stains for the histologic assessment of renal fibrosis. Examples of stains used in the assessment of interstitial fibrosis include (a) trichrome in conjunction with (c) periodic acid–Schiff, (e) Sirius Red, and (g) collagen III immunohistochemistry. In the corresponding ‘mark-up' images (b, d, f, and h) generated by a computer-assisted positive pixel count algorithm applied to the stains, tissue considered ‘positive' is ‘marked up' either yellow, orange, or red, in that order, with increasing positivity of match to the algorithm parameters; and tissue considered ‘negative,' including tubules and blood vessels, is blue. The quantitation algorithm can be used to detect the (b) ‘blue' of trichrome, the (d) ‘pink' of the periodic acid–Schiff–stained basement membranes, the (f) ‘red' of an unpolarized Sirius Red, and the (h) brown of the collagen III immunohistochemistry chromogen. (All images are at an original magnification of × 200.)