What is secondary fixative?

A secondary fixative is a chemical solution used to enhance or preserve the fixation of biological tissues after an initial fixation step. It typically follows a primary fixative and is employed to improve the preservation of cellular structures, proteins, or nucleic acids for subsequent analysis, such as microscopy or molecular studies. Secondary fixatives can improve the quality of tissue samples by providing additional cross-linking or stabilization of cellular components. Common examples include alcohols, acetone, or osmium tetroxide.