This product is a serum-free medium specifically formulated for mouse embryonic fibroblasts (MEFs). Through precisely optimized combinations of nutrients and growth factors, it efficiently promotes MEF proliferation and functional maturation, ensuring sustained secretion of key factors such as LIF and bFGF while establishing an ideal extracellular matrix. It provides a stable and reliable feeder layer system for the undifferentiated proliferation of valuable cell lines such as human embryonic stem cells and induced pluripotent stem cells. This standardized solution significantly enhances the success rate of stem cell passage culture and the reproducibility of experimental data.