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Two patients with primary amyloidosis (amyloid light chain case) and severe cholestatic jaundice are described. Liver biopsy in the preterminal stage demonstrated amyloid deposits in the perisinusoidal space and in portal tracts, and hepatocytes were atrophic because of compression by amyloid fibrils. Ultrastructural findings showed amyloid fibrils not only in Disse's space but also in the sinusoids, and the hepatocyte microvilli facing the amyloid fibrils were spicular. There were aggregates of lysosomal granules in the vicinity of bile canaliculi and some bile canaliculi were dilated with loss of microvilli. Amyloid fibrils in the portal tract compressed bile ductules, causing wide intercellular space and separated basement membranes from their epitheliums. These findings suggested disturbance in transporting not only of essential materials from sinusoids to hepatocytes but also of secretory vesicles into bile canaliculi and leakage of bile juice from small bile ductules in preterminal stage of primary amyloidosis.

Albumin immunoreactivity in the liver was examined on days 2, 5 and 10 after two-thirds partial hepatectomy by light and ultrastructural immunoperoxidase methods and the ultrastructural area of the rough endoplasmic reticulum (ER) in hepatocytes was measured. Albumin immunoreactivity was seen in the rough ER and Golgi apparatus of all hepatocytes in the hepatectomized liver and ultrastructural analysis showed a significantly greater area of rough ER on day 5 than on days 2 or 10. Albumin mRNA was studied by the in situ hybridization technique using radioisotopes and their numbers were determined visually. Albumin mRNA was present as grains in all hepatocytes and the grains varied in number during regeneration of the liver, being more abundant on day 5 than on days 2 or 10. The activity of [3H]-leucine incorporated into albumin synthesis, an indicator of translational activity, was higher on days 5 and 10 than on day 2 and was highest on day 5. In conclusion, albumin synthesis varied during liver regeneration after partial hepatectomy, being reduced at the peak of cell proliferation on day 2 and being most active on day 5.

An immunocytochemical study using a monoclonal antibody showed the presence of gamma-glutamyl transpeptidase (gamma-GTP) in the bile duct epithelium of the normal adult rat liver, while a slight immunoreactivity for gamma-GTP could be observed on the membranes of bile canaliculi (the membranes of hepatocytes facing the lumen of bile canaliculi). In hepatocarcinogenesis induced by 3'-methyl-4-dimethylaminoazobenzene, no immunoreactivity was detected in alpha-fetoprotein-positive cholangiolar "oval" cells, though it was detected on the membranes of bile canaliculi. In livers with hyperplastic nodules, gamma-GTP immunoreactivity was observed in clusters, with two different staining patterns. In one pattern, gamma-GTP was present not only on the membranes of bile canaliculi, but also on the membranes facing the Disse's space or the lateral cell surface of hepatocytes. In the other pattern, gamma-GTP immunoreactivity was seen on the membranes of the dilated bile canaliculi. In livers with developing hepatocellular carcinomas, the immunoreactivity was present on the membranes of irregularly dilated bile canaliculi in malignant cells.

Immunoreaction of alpha-fetoprotein (AFP) was detected not only in well-differentiated hepatocellular carcinoma but also in hepatocytes forming foci in livers with hyperplastic nodules during 3'-methyl-4-dimethylaminoazobenzene hepatocarcinogenesis. The subcellular location of AFP in hepatoma cells was in the rough endoplasmic reticulum, perinuclear space and well-developed Golgi apparatus around the nucleus. In livers with hyperplastic nodules it was also in some parts of the smooth endoplasmic reticulum and Golgi regions in hepatocytes in the vicinity of submembranous areas or bile canaliculi. These findings suggest that the Golgi apparatus in hepatoma cells acts mainly as an organelle for glycosylation of AFP and that the Golgi complexes in the hepatocytes in livers with hyperplastic nodules are organelles for secretion of AFP. Combined light microscopic immunoperoxidase study and autoradiography with 3H-thymidine revealed a higher cumulative labeling index in AFP-positive hepatoma cells than in non-tumorous areas. Combined electron microscopic immunoperoxidase study and autoradiography showed that hepatoma cells with AFP immunoreactivity only in the rough endoplasmic reticulum had a significantly higher labeling index than did cells with AFP immunoreactivity in both rough endoplasmic reticulum and Golgi apparatus. These findings suggest that AFP is synthesized in hepatoma cells before or during the stage of their DNA synthesis and is then transported to the Golgi apparatus.

Using light and ultrastructural immunoperoxidase techniques, we examined the distribution of hepatitis B virus (HBV)-associated antigens and the subcellular localization of hepatitis B surface antigen (HBsAg) in liver biopsies of HBsAg—positive patients with cirrhosis. The localization patterns of HBsAg in hepatocytes were membranous, cytoplasmic, festoon and inclusion body types. Cytoplasmic and festoon types were seen more often than the membranous type in pseudolobules, and hepatitis B core antigen (HBcAg)—positive cells with cytoplasmic type were distributed in the periphery of pseudolobules with active inflammation. Immunoelectron microscopy in the cytoplasmic or festoon type of HBsAg showed immunoreaction in the cisternae and on virus-like particles in the cisternae in patients with hepatitis B e antigen (HBeAg) antigenemia. Simultaneous staining of HBsAg and HBcAg revealed that hepatocytes with cytoplasmic or festoon type of HBsAg contained HBcAg—immunoreactivity. The inclusion body type of HBsAg was characteristic of liver cirrhosis with hepatocellular carcinoma (HCC); the subcellular localization of HBsAg was seen in clusters of the endoplasmic reticulum around the nucleus, and HBsAg—immunoreactivity was observed on many virus-like particles in most of the cisternae in those with HBeAg antigenemia. These findings suggest that the synthesis of HBsAg is active in patients with liver cirrhosis and that the formation of HBV is also active in those with HBeAg antigenemia and that HBV may be retained more in cirrhotic livers with hepatocellular carcinoma after proliferation than in those without it.

Immunoreaction of alpha-fetoprotein (AFP) has been described in cholangiolar "oval" cells in the early stage of 3'-methyl-4-dimethylaminoazobenzene hepatocarcinogenesis. The subcellular location of AFP in the oval cells was in the perinuclear space, rough endoplasmic reticulum and Golgi apparatus. In livers with hyperplastic nodules there were two different types of foci containing AFP-positive cells. One type had a normal nucleocytoplasmic ratio and was seen in well-preserved hepatic trabecular structures, and the other had less cytoplasm and occurred in trabecular structures in disarray. AFP-immunoreactivity in the former type was visible in the perinuclear space and rough endoplasmic reticulum but scarce in the Golgi apparatus, and in the latter type it was present in the proliferative smooth endoplasmic reticulum and in several parts of Golgi apparatus in the submembranous or pericanalicular areas. In livers with hepatocarcinoma, AFP immunoreaction was detected in well-differentiated hepatocellular carcinomas, and the subcellular location of AFP was in the perinuclear space, rough endoplasmic reticulum and many developed Golgi complexes. Therefore, AFP-positive cells in livers with hyperplastic nodules are a new cell population in hepatocarcinogenesis, and each type is morphologically different from the oval cell.