Observations on the fine structure and peroxidase cytochemistry of normal rat liver Kupffer cells

Abstract

Continuation of the investigation of sinusoidal lining cells in rat liver (120–124) has led to a description of the morphology and peroxidase cytochemistry of normal Kupffer cells. Kupffer cells were found to have a variable but often stellate shape and a surface fuzzy coat, visible after “direct” osmium fixation. Worm-like structures were restricted to Kupffer cells, as were the annulate lamellae. The dense bodies varied in shape, diameter, and density. Kupffer cells may rest on or be inserted in, but are not continuous with, the fenestrated endothelial lining (120). No gaps were observed between Kupffer cells and endothelial cells. These morphological features make it possible to distinguish the Kupffer cells from other sinusoidal lining cells. The Kupffer cells did not show fat droplets, glycogen particles, autophagic vacuoles, or multivesicular bodies. After incubation by either perfusion or immersion for the demonstration of peroxidatic activity in livers fixed for 40 seconds, only the Kupffer cells showed a positive reaction in the nuclear envelope, the RER, and annulate lamellae. This specific staining reaction therefore permits the light-microscopical recognition of Kupffer cells. Time-series incubation of Vibratome sections showed that the peroxidatic reaction in Kupffer cells is sensitive to the mode of fixation, H2O2, pH 9.0, 2 × 10−2 M AT, 10−2 M NaN3, boiling, and the omission of DAB or H2O2 from the medium. No significant retardation of the reaction occurred in the presence of 10−2 M KCN. It is concluded that a peroxidase rather than a catalase is responsible for the reaction with DAB.