As the RT-PCR and Western blot results showed, reducing PAR6 mRNA levels via plasmid-mediated delivery of shRNAs induced obvious decrease of Figagene level and PAR6 protein expression. These results indicate that PAR6 is important for the formation and maintenance of primordial follicles. Although it is reported that the germline stem cells exist in mature mouse ovaries, there is a widely held view that the mammalian neonatal ovary contains a finite Spirodiclofen stockpile of non-growing primordial follicles, and the supply of follicles declines until advancing age, when the primordial follicular pool is exhausted. It needs further elucidation whether the number of the primordial follicles could be extended by enhancing the function of PAR6. It is worth noticing that the expression of PAR6 first occurred in the somatic cells, and decreased after 17.5 dpc when the germ cells began to express PAR6 as the somatic cells invaded cysts. A signal from the somatic cells might induce the expression of PAR6 in oocytes via gap junction communication, since the expression of connexin43 protein between somatic cells and germ cells is necessary for the fetal ovary development. In order to examine our hypothesis, the fetal ovaries at 15.5 dpc were cultured with and without 20 mm/ml carbenoxolone for 4 or 8 days. The concentration was chosen from the Noradrenaline bitartrate monohydrate histology observation. The expressions of PAR6 protein and Figa gene, and the number of primordial follicles were examined at the end of the culture. A large number of primordial follicles were formed with strong expression of PAR6 in the oocyte nuclei when the ovaries were cultured for 4 days in the control group, and some growing follicles surrounded by cubical-type granulosa cells were observed with weak expression of PAR6 in the oocyte nuclei when the ovaries were cultured for 8 days. On the contrary, almost all germ cells stayed in the cyst stage after treatment with CBX for 4 days, and some of them were slightly stained for PAR6.This inhibitory effect was further enhanced after treatment with CBX for 8 days: the germ cells still stayed in the cyst stage without obvious PAR6 expression and primordial follicle formation.