Microperoxisomes in the epithelial cells of the amphibian urinary bladder: an electron microscopic demonstration of catalase and malate synthase.

All cells that comprise the epithelium of the toad urinary bladder were found to contain small ovoid to tubular membrane-bound bodies with a finely granular matrix. Such organelles were devoid of dense cores (nucleoids). These microperoxisomes reacted positively when incubated for the demonstration of catalase or malate synthase activity. In the toad liver, peroxisomes as well as microperoxisomes were seen. Histochemically, both demonstrated catalase activity; neither showed malate synthase activity. The presence of malate synthase, a glyoxylate cycle enzyme, in toad urinary bladder microperoxisomes may make these latter organelles unique among vertebrates, since malate synthase has been thought to be absent in higher animals.