FIG. 4.

Light and transmission electron microscopy of cells at 2 weeks of culture in the osteogenic xeno-free medium. Sections cut perpendicularly to the surface of seeding. (A) Light microscopy of semithin section. Bar: 10 μm. (B–F) Transmission electron microscopy of thin sections also stained with tannic acid. (B) A magnification of an area similar to that marked by square in (A). The osteoblast-like cells with a cuboidal shape show euchromatic nuclei (N), well-represented RER profiles, numerous mitochondria (M), and some lysosomal bodies (L). Mineralizing nodules are pointed out by arrow. Bar: 2 μm. (C) Desmosome-like junctions are shown (arrows). Bar: 0.2 μm. (D) Higher magnification of mineralizing nodules (arrows). Bar: 0.1 μm. (E, F) Higher magnification of ECM and fibrils (arrow). Bars respectively: 0.5 μm, 0.2 μm. Color images available online at www.liebertpub.com/tec