Cationic cacodylate iron colloid for the detection of anionic sites on cell surface and the histochemical stain of acid mucopolysaccharides.

Stable cationic iron colloid solution was prepared by mixing the Hale's iron colloid (Hale 1946; Mowry 1963) with sodium cacodylate buffer solution. The colloid particles obtained were 30-50 A in size and kept their positive charges in a wide range of pH 1.8-7.6. Observations made on rat kidney tissues proved that this iron colloid solution is promising for the detection of anionic sites of cell surface in fixed tissues as well as in living cells in place of cationic ferritin.