OBJECTIVETo construct a convenient, reliable and visual model of hair follicle development to test the hair-inductive potential of follicular cells and investigate the molecular mechanism regulating hair follicle morphogenesis and cycling.

METHODSAn open chamber was transplanted into the nude mice dorsal skin, dermal and epidermal cells isolated from newborn C57BL/6 mice skin were mixed at a specific ratio and then injected into the chamber together, 1 week after transplantation, the chamber was removed, and then, hair formation and regeneration after hair plucking was observed.

RESULTS1 week after cells implantation, the wound was moist without apparent contraction and among that pink and translucent tissue was formed. 2 weeks after implantation, the wound healed completely. 3 weeks after implantation, black hair grew from the skin was observed. 4 weeks after implantation, thick and black hair grew from the skin vertically. Completely developed structure of hair follicle was observed with paraffin section and HE staining. 1 week after plucking, new hair had regrown. The ratio of cell component was varied, whereas the other component was fixed at 1 x 10(7) cells. When the number of epidermal cells was reduced to 1 x 10(6) cells, the efficiency of hair follicle reconstitution was mostly unchanged. On the other hand, the density of newly formed hair was diminished considerably by reducing the number of dermal cells to 5 x 10(6) cells or lower. Neither epidermal cells nor dermal cells transplanted alone formed hair follicle.

CONCLUSIONSNewborn mice skin cells transplanted by chamber method can construct a complete model of hair follicle development, which can be used to test the hair-inductive potential of follicular cells and investigate the molecular mechanism regulating hair follicle morphogenesis and cycling.