Paraformaldehyde Fixative is commonly used in immunohistochemicstry and immunocytochemistry. It is relatively mild and can well preserve antigenicity and ultrastructure， suitable for long-term storage of tissue speicimen and cell sections in tissue and cell immunohistochemistry research. 4% PFA， RNase/DNase free is mainly composed of PFA， phosphate salts， enzyme-free sterile water， pH7.2-7.4， suitable for fixation of most tissue and cells， especially for experiments on RNA and DNA as it can well protect structure and RNA/DNA in tissue and cells. This product is for scientific research only， not supposed for clinical diagnosis.