Capillarogenic activity of MMECs compared with HUVECs. Cells were seeded on matrigel in the specific complete medium and after an 8-hour incubation their 3-dimensional organization was examined planimetrically. A patient's cells formed (A) branching, anastomosing tubes with (B) multicentric junctions, resulting in a network of capillary-like structures and (C) extroversions of cell membranes (arrows), suggesting sproutive growth. (D) HUVECs formed a loose and poorly organized network. The network in (A) has area percentage of 29.2, length of 7670, branching of 43, mesh of 38; that in (D) has area percentage of 16.3, length of 4110, branching of 21, mesh of 12. Bar = 70 μm (A,D), 30 μm (B), and 18 μm (C).