FIG. 1.

A general outline of differentiation is shown (1A). Blue arrow indicates a typical area of flat cells of squamous epithelium. Red arrow—the central clusters of advanced differentiation. Green arrow—undifferentiated cells, yellow arrow—the cells of transitional zone. E-Cadherin (CM14) staining showing that adherens junction was present in hESCs and compromised in transitional zone, but became pronounced on differentiation (2A). F-actin cytoskeleton (H14) extended around the inner surface of the cell membrane typical of the epithelial cells “circumferential actin belt.” Cytoplasmic stress fibers became apparent when cells acquired epithelial morphology (1, 2B). CK18 (H14) is drastically up-regulated on epithelial differentiation; overlay with Oct4 (2C). RT-PCR analysis (H9) of CK18 expression showing gradual increase of the proportion of epithelial cells on differentiation progression (1C). Expression of Lamin A/C emerging in differentiating areas (3A) concurrent with Oct 4 down-regulation (3B). A developing network of tubulin in the differentiated cells (H14) is shown (3C). hESC, human embryonic stem cell; RT-PCR, reverse transcription–polymerase chain reaction.