Karnovsky fixative, developed by M. J. Karnovsky, is a fixative for electron microscopy. Solution The stock solution for Karnovsky fixative is as follows: 2.0 g paraformaldehyde 25 ml distilled water 1M sodium hydroxide 2 - 4 drops 50% glutaraldehyde 5.0 ml 0.2M cacodylate buffer, pH 7.4, 20.0 mL Mix the paraformaldehyde with 25 ml of distilled water in a 125 ml Erlenmyer flask. Heat to 60°C on a stir plate. When moisture forms on the sides of flask, add sodium hydroxide and stir until the solution clears. Cool solution under the faucet. Filter, add glutaraldehyde and 0.2M buffer, pH range 7.2 to 7.4. Modified solutions Karnovsky's fixative solution is often modified for specialized applications. For example, 2% paraformaldehyde, 2.5% glutaraldehyde in 0.1 Molar sodium phosphate buffer (pH 7.4) has been used to study the ultrastructure of renal pelvis fragments. References External links MSDS: Karnovsky's fixative Electron microscopy