Histochemical studies of uric acid in some insects. I. Storage in the fat body of Periplaneta americana and the action of the symbiotic bacteria

An improved histochemical method for uric acid consists in precipitation as silver magnesium urate combined with fixation of the tissues in formol/glutaraldehyde followed by argentaffin reaction with silver nitrate buffered with “tris” to pH 9.5. This reveals urates both in solid deposits and in solution in the tissues. Polyphenols concerned in sclerotin formation also react. In Periplaneta, uric acid synthesized in the trophocytes is carried by intracellular and intercellular channels to form the intercellular deposits of solid spheres. The symbiotic bacteria in the mycetocytes in contact with the deposits appear to metabolize the uric acid and they disperse and eliminate the deposits.