Immunological detection studies of intracellular antigens on structures such as cytoplasmic and/or nuclear enzymes, requires the permeabilization of the cell membrane in order to allow interaction of the antibody with its intended target. In order to allow recognizable cellular integrity after permeabilization a fixation step involving cross-linking or denaturation is required. IntraCell is developed for use with all flow cytometers and reagents remains intact the cell surface marker expression and the cell properties of FSC and SSC. The product includes: Reagent A) Fixative solution; Reagent B) Permeabilization solution.