Morphological changes after Schwann cell (SC)-cell like cell induction. Undifferentiated human placenta-derived multipotent stem cells (PDMCs) at passage 4 exhibited fibroblast-like morphology under a phase contrast microscope (A). After incubation with β-ME, PDMCs began to elongate and left a contracted cell body with several process-like extensions (B). After incubation with RA, cells further retracted their cytoplasm to become spindle shaped and produced more obvious halations (C). After induction with neurotrophic and growth factors, human PDMCs differentiated into SC-like cells on days 5, 8, 11, and 14 (D, E, F, G, respectively). A higher percentage of morphological change was exhibited from days 5–8 (D, E). SC-like cells retained their morphology on day 11 (F). Some SC-like cells failed to maintain their morphology and even died (G). Relationship between morphology and cell density; morphological changes of cells were less obvious in areas with a higher cell density (H) than in those with a lower cell density (I). Bar, 100 μm.