Engineered mammary epithelial tissues rapidly align adjacent collagen fibers. (A–E) Confocal images of circular EpH4 mammary epithelial tissues (red) and their surrounding collagen matrix (white) taken at (A) 0 h, (B) 2 h, (C) 4 h, (D) 6 h, and (E) 24 h after tissue seeding. (F–J) Corresponding fiber alignment relative to the tissue surface at (F) 0 h, (G) 2 h, (H) 4 h, (I) 6 h, and (J) 24 h after tissue seeding. The scale bar represents 50 μm. To see this figure in color, go online.