HPSCs cultured on different surfaces. Schematic diagrams illustrate the arrangement of cell adhesion molecules (CAMs), ligands and substrates (where appropriate) of the three major types of culture surfaces used for maintenance of human pluripotent stem cells (hPSCs). (A) Feeder cells, (B) extracellular matrix (ECM) extracts and (C) chemically defined culture surfaces. (D-F) Phase contrast images of hPSCs cultured on one example of each surface type, murine embryonic fibroblasts, GeltrexTM and Corning SynthemaxTM respectively. (D*-F*) Magnified regions of D-F. hPSCs cultured on each surface display a typical morphology with compact colonies of cells with prominent nucleoli and high nuclear-to-cytoplasmic ratio.