Esterase-Rich Bodies in Osmium-Fixed Cells of Rat Kidney and Liver

In 1952, Holt and Withers (1) described esterase-rich intracellular bodies in rat kidney and liver. In kidney, these bodies were spherical and were present chiefly in the proximal convoluted tubules. In liver, they appeared to be more irregular and were aligned along the bile canaliculi. The indoxyl method used for the demonstration of this enzyme by Holt (2) has recently been further improved through the use of 5-bromo-4-chloroindoxyl acetate as substrate. This substrate, like the 5-bromoindoxyl acetate used earlier (1), provides for the visualization of these intraceUular bodies, but with greater precision (3). In both procedures Holt utilized tissue fixed in formol-calcium. Pearse (4) has observed that frozen-dried sections showed the esterase-rich bodies and Holt (unpubfished experiments) has seen them following a wide variety of fixatives. We wish here to record the observation of their presence in tissue fixed in buffered osmium tetroxide (currently regarded as excellent for the preservation of the fine structure of cells), and the survival of the dye during alcohol dehydration, benzene clearing, and paraffin embed-