Fig. 8. Stem cell amplification and fate in culture. (A) Clonogenicity assay with 2.5 x105 total keratinocytes from 2-month-old control (Ct) or KO mice. (B) Clonogenicity assay with 105 basal keratinocytes from Ct or KO newborns (see Materials and Methods). Keratinocyte colonies are red, fibroblast-feeder layer is blue. (C) Microscopic view of Ct or KO (arrows) colonies. Note that KO colonies are constituted by one or three flattened cells only. (D) Immunofluorescence on Ct or KO keratinocytes in culture. Ks stands for keratins K5 and K6 (mix of two antibodies to detect keratinocytes stained in green), nuclei in blue (DNA, DAPI). A 2 hour BrdU incubation was done after 5 and 21 days (stained in red). Bar, 20 µm. D, days.