Isolation and biological characteristics of rat hair follicle stem cells. Primary cell culture on (a) day 3, (b) day 7 and (c), (d) day 14. Rat hair follicle stem cells (HFSCs; P2) (e) before and (f) after purification. (g) Quantitative polymerase chain reaction results of six correlated genes in rat HFSCs; ACTB was used as the reference gene. (h) Immunofluorescence staining for expression of cytokeratin (CK) 15, integrin α6 and integrin β1. (i) Growth curves of different generations of HFSCs. Scale bars: 100 μm (a to c, e, f, h); 250 μm (d). Ct, cycle threshold; P, passage.