Multiphoton microscopy for tumor regression grading after neoadjuvant treatment for colorectal carcinoma

Figure 3 Representative multiphoton microscopy images from a muscularis propria specimen after neoadjuvant radiochemotherapy, color-coded green represents the second-harmonic generation signal and color-coded red corresponds to the two-photon excited fluorescence signal. Remaining malignant glands are dispersed deep within the rectal muscularis propria. A: Multiphoton microscopy of second-harmonic generation from collagen; B: Two-photon excited fluorescence of carcinomatous cells, inflammatory cells, and elastin; C: Overlay image (scale bar: 100 μm); D: Hematoxylin and eosin staining of an adjacent section (magnification × 40). Tumor cells in post-treatment rectal carcinoma show marked changes, and can become more solid (blue arrows) or retain a glandular growth pattern (white arrow). Fragmented elastic fibers are denoted by pink arrows.