Changes in ovarian hardness and elasticity affect the development and function of secondary follicles

Various cells are localized to appropriate positions in tissues and induced a unique gene expression and functions. In this study, we show for the first time that age-related changes in ovarian hardness and elasticity are linked to abnormal signal transduction affects in secondary follicles. Immature ovaries had lower hardness and elasticity indices, whereas aged ovaries had lower elasticity and higher hardness indices than mature ovaries. Importantly, an optimal hardness and elasticity is important for normal gene expression profile of secondary follicles. We reproduced the ovarian hardness and elasticity using alginate beads with different concentration and viscosities, for three-dimensional culture of secondary follicles. In the aged-ovarian hardness group, follicular diameter decreased significantly and the expression of inflammation-related markers increased significantly. In the immature-ovarian hardness group, follicular diameter increased significantly and the expression of differentiation and proliferation markers increased significantly. The mechanism transmitted the hardness and elasticity to the change of gene expression was that YAP, transmit the physical conditions to nucleus via actin network, was significantly increased in both condition of immature or aged ovary. The abnormal signaling associated with the age-related changes in ovarian hardness and elasticity may aid in the development of treatments for abnormal follicular development in infertility.