ALBUMIN LOCALIZATION IN RAT-LIVER PARENCHYMAL-CELLS

Abstract

The localization of albumin in hepatocytes was re-investigated using immunocytochemistry (ICC) on ultrathin cryo-sections of rat livers, which were immersion or perfusion-fixed with paraformaldehyde or a mixture of paraformaldehyde and glutaraldehyde. The sections were indirectly labeled with rhodamine-conjugated IgG or with 8 nm protein A-colloidal gold particles. Perfusion-fixation is obligatory for a proper localization of albumin. After perfusion fixation, all hepatocytes of fed and fasted rats were uniformly labeled. At the subcellular level albumin was localized in hepatocytes in the membrane-bound compartments of the entire secretory pathway, i.e., the rough and smooth ER [endoplasmic reticulum], peripheral Golgi vesicles, all Golgi cisternae and the secretory granules. Concentrations of albumin appeared mainly to occur at the cis-Golgi side.