Fig. 2.

Immunostaining of myocyte interfaces with microstructures. (a, b) Staining of cardiac myocytes for paxillin (green), sarcomeric α-actinin (red), and nuclei (blue) show punctate focal adhesions in control gels but accumulation at regions of microstructure contact (scale = 20 μm). Note that microstructures also fluoresce blue. White arrowheads label focal adhesions along the microstructure. (c, d) Antibody labeling of N-cadherin (green) and α-actinin (red) reveal that small clusters of myocytes (2 cells) also interact with microstructures. Arrowheads mark regions of cell-cell contact. (e) In gel alone, myocytes (α-actinin, red) exhibit a common spindle shape. Striations are visible in the inset and are identified with arrowheads. (f) Myocytes form perpendicular, oblique, or parallel associations with randomly-oriented microstructures in 3D, with (g) showing a series of confocal image slices over an 8 μm thickness