Figure 4. Time-dependent change of three-dimensional culture at a density of 2.6×104 cells/cm2. Microscopic images at 0 (A), 2 (B), 4 (C), and 6 days (D) are shown. From a single cell (A), elongation occurred to generate structures (B and C), and finally complex structures were observed (D). Scale bars, 100 µm.