Objective To reconstitute hair follicles in mice using graft chambers,and to study the effect of different cell types on hair follicle regeneration.Methods Full-thickness skin was obtained from the back of C57BL/6 neonatal mice.Then,epidermal cell suspensions were prepared by shredding epidermis after trypsinization,hair follicles and dermal cells were collected by filtration,low-speed centrifugation and density gradient centrifugation,and hair follicle epithelial cells were obtained via trypsinization of hair follicles followed by filtration.Nude mice were classified into four groups to be transplanted with epidermal cells + follicular buds,dermal cells alone,epidermal cells + follicular buds + dermal cells,follicular epithelial cells + dermal cells,respectively.The cells were implanted into the dorsal skin of nude mice using fold chambers.After the grafting,the growth of skin and hairs was observed at the grafted sites on week 1,2,4 and 8,and skin specimens were obtained on week 2,4,and 8 for histological study of hair follicles using hematoxylin-eosin staining.Results After grafting,the chambers on the back of nude mice began to shed with crust formation on week 1; stunted hairs came out and follicle-like structures were seen under the microscope on week 2 at the grafted sites,normal hairs were observed on week 4 and 8 in all the mice except for those transplanted with epidermal cells + follicular buds,and the growth of hairs in mice grafted with epidermal cells + follicular buds + dermal cells and mice grafted with follicular epithelial cells +dermal cells was superior to that in mice grafted with dermal cells alone.Conclusions Hair follicles can regenerate after hair follicle cell transplantation into dorsal chambers in nude mice.Both epidermal cells and dermal cells play indispensable roles in hair follicle reconstitution.