Figure 1.

Confocal Brillouin microscopy maps cartilage architecture, identifying differences between chondrocytes and ECM (a) Schematic representation of the distal phalanx in digit II, generated with Keynote. The red rectangle indicates the imaged area, shown in (b). (b)(i) Brightfield image of probed region. Dashed lines show the position of the phalanx. (ii) Widefield fluorescence image using CAGGs:GFP reporter line. All cells were eGFP⁺. Red rectangle shows region probed with the Brillouin microscope shown in (c). c, cartilage; e, epidermis; is, interstitial space. Scale bar: 50 µm. (c) Brillouin elastic contrast ($\overline{{\nu }_B}$) maps for the region shown in (b). The Brillouin elastic contract (normalized Brillouin frequency shift) is indicative of the elastic properties. Dashed oval shows segmented cell as an example of quantifications shown in (d). (d) Quantification of average Brillouin elastic contrast inside cells (chondrocytes) and the surrounding ECM. N_C = 20, N_A = 4, t-test, *** p < 0.001.