Suitable for both electron and light microscopy. Easily penetrates large blocks of tissue. When used in combination with glutaraldehyde, it fixes delicate tissues such as brain in vascular perfusion. Avoids the problem of having to depolymerize paraformaldehyde. Use in Karnovsky's fixative in conjunction with your own buffer system.Store at room temperature tightly sealed as exposure to air encourages the oxidation of formaldehyde to formic acid. Cold temperatures storage encourage the formation of trioxymethylene as a white precipitate.