Objective   To detect the expression pattern of Wnt10b in the hair follicles of mice at different age and explore its importance.    Methods   The expression of Wnt10b in the back skin of mice at anagen phase (1

7 and 15 d after birth)

catagen phase (18 d)

telogen (23 d) and secondary anagen phase (29 d) was detected by reverse transcription-polymerase chain reaction (RT-PCR). The localization of Wnt10b in the hair follicle of same skin area of mice was measured by immunohistochemical method. The expression of Ki67 was studied at the same time.    Results   Wnt10b mRNA was strongly expressed in the skin at anagen phase (P0.01)

reached its maximum at the middle of anagen phase

and slightly expressed at catagen and telogen phases. In the secondary cycle

Wnt10b transcripts level in the early anagen phase was a little bit higher than at catagen and telogen phases. Wnt10b protein was specifically expression in the hair matrix of anagen follicles. No such protein was detected at catagen and telogen follicles. The expression of Wnt10b appeared in the secondary hair germ at early anagen in secondary cycle.    Conclusion   The expression of Wnt10b is strictly special in time and space. Wnt10b is specifically localized in the hair matrix at anagen

and in the secondary hair germ at early anagen in the secondary cycle. Accordingly

our results indicate that Wnt10b may promote the proliferation of matrix cells

and regulate the cyclical growth of hair cycles.