In order to investigate the relationship between PAR6 expression and apoptosis of germ cells, we performed immunohistochemistry with the anti-PAR6 antibody or TUNEL at the two adjacent serial sections of new born mouse ovaries. The nuclei of oocytes within primordial follicles and some germ cells showed positive immunolabelling for PAR6 but Isoxicam negative immunolabelling for TUNEL, and none of the TUNEL positive germ cells were stained with the PAR6 at any time studied. These results indicate that the germ cells with PAR6 do not show apoptosis, and others without PAR6 may fail to be enclosed into follicles and finally undergo degeneration. Some germ cells with PAR6 negative staining also showed negative immunolabelling for TUNEL. The possible reason is that PAR6 reactivity loses in the germ cells prior to the time when they became positive in the TUNEL assay. Similarly, the expression of Figa gene in the anti-PAR6 antibody treatment obviously decreased, compared with the control. Figa gene is expressed throughout the early developmental stages, including oogonia proliferation via mitosis, transformation into oocytes via meiosis, and primordial follicle formation, whereas progressive loss of its expression is closely associated with germ cell degeneration and follicle formation failure. For more persuasion, we employed a short hairpin RNA-mediated gene knock-down approach. We got the optimal transfection efficiency after experiments with different transfection conditions. Compared with control, the ovaries treated with shRNA exhibited structural disorganization characterized by nests of germ cells without PAR6. The number of follicles declined in PAR6-deficient ovaries, but the number of naked germ cells increased. Unfortunately, the total number of germ cells also declined like the experiment of anti-PAR6 antibody culturing. In the period of forming primordial follicles, the germ cells which couldn��t be surrounded by pregranular cells would undergo apoptosis.Oseltamivir acid Therefore, the possibility of the reduction in total germ cell number in the antiPAR6 antibody and shRNA groups was that the PAR6 negative germ cells cannot form primordial follicles and then died.