|  MSCs were isolated from bone marrow at high purity. Cells expressing CD90.
      1 and CD29 were identified using fluorescence-activated cell sorting. Cells
      consisted of a heterogeneous cell population with a predominant spindle
      morphology. Cells cultured for three days (A) and one (B), two (C), and three
      weeks (D) were photographed, and MSCs proliferated to form a small colony
      on day 3. A large colony of densely distributed spindle- and triangle-shaped
    MSCs formed after three weeks. | 
| Figure 1: Phase-contrast micrographs of MSCs at three days and one, two, and three weeks of primary culture. |