FIG. 4.

Fourier transform–infrared imaging spectroscopy (FT-IRIS) images and histology of repair and adjacent normal tissue in placebo and TP-508 animals at 3 and 6 weeks postsurgery. Row 1, collagen distribution; row 2, proteoglycan (PG) distribution; row 3, alcian blue–stained histology for PG distribution (magnification, 10 × ); row 4, PLGA distribution (the color scale was adjusted in the 6-week group to facilitate observation of the remaining PLGA); row 5, collagen integrity; row 6, collagen orientation. In all IR images (except collagen orientation), scale bars reflect relative quantity of imaged component, where red is greatest and blue is least. For collagen orientation, red indicates fibrils parallel to the articular surface and dark blue indicates fibrils perpendicular to the articular surface. The defect region was filled with repair tissue at 6 weeks in many samples from both the TP-508 and placebo groups. Stratification of collagen fibril orientation was apparent in the normal cartilage adjacent to repair tissue in all samples, but no stratification was apparent in the repair tissue.