Media 199 were originally developed for nutritional studies of chick embryo fibroblasts and formulated as a completely defined media for the culture of primary explants. The medium is useful with serum for growth of a broad range of cells, particularly for non-transformed cells and are widely used for vaccine production, primary pancreatic explants, and lens tissues. Media 199 are formulated with either Earle's salts or Hank's salts Media utilizing Earle's salts are buffered with a bicarbonate/carbonic acid system and will maintain pH in a CO2 incubator. Use of Earle's salts in atmosphere conditions will result in rapid rise in pH of the culture medium. This product is for research use only. It is not approved for human or animal use, or for application in in vitro diagnostic procedures.