p-Toluenesulphonic Acid as a Fixative
p-toluenesulphonic acid in aqueous solution is introduced to histologists and recommended for fixation of the central nervous system by a three-step procedure: flushing the blood-vessels with a saline solution, filling the vessels with the fixative, and delaying the autopsy. With rats and guinea-pigs as test objects, a solution of at least 0.5 M gave excellent results, as evidenced by the minimum of cellular shrinkage, the absence of perivascular and perineuronal spaces, and the clarity of cellular membranes and basiphil material. The neurones, neuroglia, microglia, and blood-vessels were well defined when stained by conventional histological techniques. Cytological details became more prominent because the tissue had shrunk less than in routine preparations. The acid is non-volatile, colourless, pleasant to handle, and low in price.