Structure of engineered tissues compared under static and flow conditions. Top panels show confocal microscopy images of rhodamine-phalloidin (red) and cell nuclei (blue) in (A) RAEC-only, (B) RMSC-only, and (C) RAEC-RMSC coculture gels for 3 days in static culture. Bottom panels show collagen gels cultured under flow at 5 mL/min for 3 days. (D) RAEC-only, (E) RMSC-only, and (F) RAEC-RMSC coculture. (C, F) Three-dimensional reconstruction of confocal microscopy images, showing spatial distribution of the microvessels formed in the absence and presence of flow. Scale bar = 50 μm. The direction of the flow is from top to bottom in the plane of the image. Color images available online at www.liebertonline.com/ten.