Horizontal scaffold cross-sections stained with Sirius Red. The dashed line circles represent the real diameter of the channels (L, 3 mm; M, 1.5 mm; S, 1 mm). (a–c) L, M and S channels of scaffolds cultured under static conditions at the top of the scaffold. (d–f) L, M and S channels of scaffolds cultured under static conditions at the bottom of the scaffold. (g–i) L, M and S channels of scaffolds cultured under perfused conditions at the top of the scaffold. (j–l) L, M and S channels of scaffolds cultured under perfused conditions at the bottom of the scaffold. Cells are located within channels and the pores of the scaffold. Scale bar, 500 µm. (Online version in colour.)