FIG. 1.

Morphological analysis of glial restricted progenitors (GRP) differentiation profiles using phase contrast microscopy. Human GRP were differentiated for six or 10 days with bone morphogenetic protein 4 (BMP-4), ciliary neurotrophic factor (CNTF), or basic fibroblast growth factor (bFGF) and evaluated by phase contrast microscopy for morphological characteristics. Treatment with fetal bovine serum (FBS) was utilized as a morphological reference. Panels B–E (day 6) and F–I (day 10) show the morphological phenotypes relative to day 0 undifferentiated control cultures (Panel A). BMP-4 and CNTF resulted in the generation of heterogeneous, albeit morphologically distinct, process-bearing cells. bFGF, in contrast, maintained cells in their original GRP state. hGRP differentiated with FBS generated a near homogenous, flat, fibroblast-like morphology, and served as a morphological reference. Scale bar=25 μm.