Leibovitz’s L15 medium was originally developed without a sodium bicaronate buffer system for use in non-CO2 equilibrated environments. It is buffered by phosphates and the amino acid L-arginine, along with L-histidine and L-cysteine. The formation of acid metabolite byproducts is prevented by replacing glucose with galactose and sodium pyruvate. Examples of usage include the propagation of HEP-2, monkey kidney cells and primary explants of embryonic and adult human tissue. Leibovitz’s L-15 supports established cell lines as well as primary explants of embryonic and adult human tissue.