Follicular fluid is the internal environment where follicular cells grow and proliferate，and the changes of its components are closely related to the functional status of follicular cells. In recent years，it has been found that exosome，a double-layer membrane vesicle with a diameter of about 30-150 nm，exists in many biological fluids，and its mediating role in many physiological and pathological processes has been revealed. The researchers also identified exosomes in follicular fluid and found that they are closely related to the growth and proliferation of follicular cells，indirectly influencing oocyte status，which is important for assessing oocyte quality.