6.3. Electron microscope

in vitro [45]. Another study [46] reported that MSCs retained their multilineage differentiation potential till passage 10 (P10) and maintain high levels of telomerase activity and long telomere length up to P10, but steady decline in the efficiency of proliferation in all cell populations after P10. Furthermore, MSCs showed a marked increase in the time required for cell doubling and showed an enlarged, flattened cellular morphology at P15, after which they ceased to undergo cell division but remained viable in culture. Thus, cells from passage 9 were used for differentiation as it was needed to obtain sufficient cell numbers for use through

Studying the behavior of MSCs in vitro has become an urgent need to give more insights on their behavior in vivo and their mechanisms in initiating osteogenesis. Indeed, histological examination of MSCs is one of the main goals for studying their morphology in vitro by light microscope. Although it is a primary step, yet, it is not sufficient to rely on it alone, to detect their behavior during their differentiation process, and as such it has to be accompanied by

MSCs are characterized by being star-shaped cell with thin long processes [48]. Using hematoxylin and eosin stains, MSCs are characterized by pale cytoplasm, large vesicular nucleus

Regardless of the issue of origin, all MSCs share characteristics by consensus definition: they are spindle-shaped and plastic-adherent. In our study, [38] isolated human bone barrow MSCs

Figure 1. Light microscopic picture of the umbilical cord showing MSCs with many thin processes (arrow). Each cell

extensive cell quantity amplification and later passages were avoided [47].

32 Stromal Cells - Structure, Function, and Therapeutic Implications

ultrastructure examination to correlate between their morphology and behavior.

6. Histology

6.1. Light microscope

and multiple thin processes (Figure 1).

6.2. Phase contrast microscope

exhibits a vesicular nucleus. Scale bar 50 μm.
