C57BL/6 Mouse Embryonic Fibroblasts from AcceGen are isolated from tissue of pathogen-free laboratory mice. Mouse Embryonic Fibroblasts are grown in T25 tissue culture flasks pre-coated with gelatin-based solution for 0.5 hour and incubated in AcceGen Culture Complete Growth Medium generally for 3-7 days. Cultures are then expanded. Prior to shipping, cells are detached from flasks and immediately cryo-preserved in vials. Each vial contains at least 2x10^6 cells per ml and is delivered frozen. Mouse Embryonic Fibroblasts are negative for bacteria, yeast, fungi, and mycoplasma. Cells are tested for expression of marker using the antibody of anti-FSP1/S100A4 （Millipore USA） by immunofluorescence staining. Cells can be expanded for 3-6 passages at a split ratio of 1： 2 under the cell culture conditions specified by AcceGen. Repeated freezing and thawing of cells is not recommended.
