Cytoplasmic blood plasma inclusions of canine hepatocytes demonstration by immunoperoxidase-labeling method

Cytoplasmic inclusions in canine hepatocytes were scattered abundantly throughout hepatic lobules. They were mainly round, measured 3 microns to 20 microns in diameter, stained eosinophilic with hematoxylin and eosin stain, and were positive for diastase-resistant periodic acid-Schiff and phosphotungstic acid hematoxylin stains. Immunoperoxidase staining revealed that most of the inclusions were positive for such blood plasma components as albumin, immunoglobulins G, M, A, and transferrin. Ultrastructurally, the inclusions were granular, floccular, fibrillar, or homogeneous with a low or high electron density. Fibrin fibers and erythrocytes were occasionally recognized in the inclusions. These inclusions were considered to have derived from engulfment of blood elements into hepatocytes, probably as a result of increase of the intrasinusoidal blood pressure.