Objective  To detect the expression pattern of transcription factor c-Myc in synchronized hair follicles in mice at different hair follicle stages and explore its possible significance.   Methods  Pine wax mixture to removal hair shafts was used to synchronized mouse back skin hair follicles. Totally 15 female C57BL/6 mice (hair follicles in the anagen phase) were randomly divided into 3 groups for immunohistochemical staining (IHC)

RT-PCR and Western blot analysis respectively. The mice were killed in 5

10

16

20 and 25 d after the infliction. The intensity and localization of c-Myc in different hair follicle stages were detected.   Results  The expression intensity of c-Myc were different in all 5 time points in the skin. The results of Western blot analysis and RT-PCR are consistent

showing that c-Myc was strongly expressed in the middle and late anagen phase and in the catagen phase while weakly in the early anagen and telogen phases. IHC results showed that c-Myc was mainly distributed in the inner root sheath (IRS) and the matrix in the anagen phase

and rudimentary IRS in the catagen phase. There was no expression in the telogen phase. Besides

c-Myc expression was strong in the sebaceous glands in all hair follicle stages.   Conclusion  c-Myc is specifically localized in the IRS and matrix during the anagen phase

and the rudimentary IRS in the catagen phase. Our findings reveal that c-Myc may play an important role in terminal differentiation of hair follicle keratinocytes.