A new method for the cytochemical staining of cells immobilized in agarose

A quick, simple and inexpensive technique utilizing an isotonic matrix of semi-solid agarose for immobilizing channel catfish (Ictalurus punctatus) peripheral blood leucocytes onto microscope slides before cytochemical staining is described. The technique was demonstrated to be superior to the more conventional means of immobilizing cells for procedures requiring either fixed (Sudan Black B and nonspecific esterase stains) or viable (Nitro-Blue Tetrazolium stain) cells. Although the agarose immobilization technique was developed with channel catfish leucocytes, its utility with other fragile cell populations seems likely.