This study was conducted to explore the role of Smad9 on follicular development in mice and provide new ideas for the study of follicular growth and its regulation mechanism.Sixweek-old female Kunming mice were randomly divided into 3 groups and injected intraperitoneally with physiological saline,bone morphogenetic protein-4(BMP4)and Smad9 inhibitor(LDN-193189),respectively,which were used as the control group,BMP4 group and LDN group.After48 hours,the ovaries were collected to make paraffin sections.Folli...