Five apparently healthy males in whom an Au-antigen positive reaction persisted consented to a percutaneous liver biopsy. The tissue was fixed in buffered osmium tetroxide, dehydrated in ethanol and embedded (Epon). The sections were stained with uranyl acetate and lead citrate and examined with an electron microscope (Philips EM 300). Several parenchymal cells with distortion of the elements of endoplasmic reticulum were noted in two of the five specimens. A filamentous or tubular content in the vicinity of round to elipsoid structures was seen in the cisternae (Fig 1). These structures were bounded by a membrane similar to that of the endoplasmic reticulum and contained an electron opaque core, which was often eccentric (Fig 2). Since that time, similar structures, not illustrated, were seen also in sections of pellets obtained from sera of Au-antigen carriers.
We believe that the particles found in the liver represent the intrahepatic form of the