Fig. 2.

Channel 1 (375 to 410 nm) fluorescence LT increases with distance from articular cartilage surface ($n=3$). (a) Representative cross-section and zonal FLIm image of native bovine articular cartilage. $\text{Scalebar}=1\mathrm{mm}$. Dashed line represents estimated location of cut of superficial, middle and deep zone. (b) Violin plot of LT distribution of different zones of articular cartilage acquired through zonal and $x$-section imaging. The LT of superficial zone is significantly lower than that of middle and deep zones (***$p<0.001$). (c) A box plot of average LT versus distance from cartilage surface for all samples ($n=3$). Each box represents all data points from all samples at the corresponding distance from cartilage surface. Five values are highlighted: the extremes, the upper and lower quantiles, and the median. A clear increase of LT with distance from cartilage surface is observed. The increase is most prominent within the first 0.5 mm of cartilage surface.