Figure 2.

Engineered mammary epithelial tissues contract inward, imposing a strain that correlates temporally with ECM alignment. (A) Percentage of unaligned fibers over time around EpH4 mammary epithelial tissues. The mean ± SE of three independent experimental replicates is shown. (B) Radial strain exerted by tissues over time. The mean ± SE of three independent experimental replicates is shown. (C) Number of fibers surrounding engineered tissues per subimage over time. The mean ± SE of three independent experimental replicates is shown. (D–F) Time-lapse confocal images of a representative circular epithelial tissue (red) and its surrounding collagen matrix (white) taken at (D) 0 h, (E) 2 h, and (F) 4 h after tissue seeding. The dashed yellow circle indicates the initial geometry and white arrows indicate collagen fibers aligned adjacent to the tissue surface. (G) Changes in fiber angle of eight individual fibers relative to the tissue surface from 0 to 6 h. Gray shaded region indicates fiber angles that are binned as aligned (i.e., oriented approximately perpendicular to the tissue surface). (H) Change in length over time of individual fibers adjacent to tissues. The mean ± SE of fibers from three independent experimental replicates is shown. (I) Change in the distance from individual fibers to the tissue surface over time. The mean ± SE of fibers from three independent experimental replicates is shown. The scale bar represents 50 μm. To see this figure in color, go online.