Abstract: Objective To explore the changes of DNA content of normal epidermal cells during proliferation and terminal differentiation. Methods DNA content of human epidermal cells in each layer from normal human skin (10 cases) was determined with adherent cell analysis and sorting cytometer (ACAS570).The tissue sections with 10μm thick were stained with acridine orange (AO), and evaluated by DNA integrated fluorescence value (IV), average fluorescence value (AV), and scanning area (A) of epidermal cells in each layer with ACAS570. Results The results showed that IV,AV, or A were higher in spinous cells than those in cells of other layers(P<0.01), but there was no difference in cells of the other layers (P>0.05). DNA fluorescence was still present in the lower horny layers, and almost disappeared in the upper horny layers. Conclusion The results suggest that total level of DNA content, density or area of distribution are higher or larger in cells of the spinous layer than those of the other layers. These data demonstrate that the high level DNA synthesis takes place in the spinous layer, inhibited in the basal cells, not degraded in the granular layer where DNA may be degenerated, and degraded in the horny layer.

Key words: Epidermis, DNA