Multiphoton microscopy (MPM) and corresponding histology images of the prostate gland. (A,B) Low-magnification image of human prostate gland showing concretions. The MPM image (A) shows acini containing structures that are probably concretions (green; shown by arrows) and collagenous stroma (red). Panel B shows an H&E-stained sample from a corresponding area; (C,D) higher-magnification view of prostatic glands. The MPM image (C) shows acinar cells (green) and collagenous stroma (red). Panel D shows image of H&E-stained sections from a corresponding area; (E,F) Prostatic acinus and nearby artery (on the capsule) showing differing autofluorescence signals. Panel F shows H&E-stained sections from corresponding areas of the same specimen. Color-coding of MPM images: red, SHG (355-420 nm); green, short-wavelength autofluorescence (420-530 nm); blue, long-wavelength autofluorescence (530-650 nm). Scale bars: A, E, 200 µm; C, 50 µm (8). H&E, hematoxylin and eosin.