A post-embedding immunoelectron-microscopic demonstration of apolipoprotein-B-containing lipoprotein particles in hepatocytes of fetal rats.
We used the protein-A gold technique to demonstrate the presence of apolipoprotein-B in ultrathin sections of fetal rat liver tissue. It was possible to show for the first time that the electron-dense, osmiophilic particles with diameters of 20-40 nm located within the RER cisternae and Golgi complexes of fetal rat hepatocytes contain apolipoprotein-B components and therefore are lipoproteins. After specific labelling an accumulation of gold label was observed on the RER cisternae, Golgi cisternae and the Golgi-associated secretory vesicles of hepatocytes. The specificity of this labelling pattern was assessed by comparison with cytochemical controls. Our qualitative findings were confirmed by a quantitative analysis of the mean labelling intensity (mean number of gold particles per square micron of the surface area of a particular cellular compartment) on the RER, Golgi complexes, mitochondria, nuclei and the remaining cytoplasm of hepatocytes. It is concluded that the hepatocytes of fetal rats are capable of forming apolipoprotein-B-containing lipoprotein particles. With respect to the size-distribution pattern of the observed intra-hepatic lipoprotein particles, we suggest that the hepatocytes of fetal rats produce lipoproteins of the low- and very low-density-lipoprotein type.
D000818:Animals; D001055:Apolipoproteins B / Q000032:analysis* / Q000276:immunology; D004721:Endoplasmic Reticulum / Q000032:analysis; D005260:Female; D005333:Fetus / Q000032:analysis*; D006056:Golgi Apparatus / Q000032:analysis; D006651:Histocytochemistry; D006652:Histological Techniques; D008077:Lipoproteins, LDL / Q000097:blood; D008079:Lipoproteins, VLDL / Q000097:blood; D008099:Liver / Q000032:analysis* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008930:Mitochondria, Liver / Q000032:analysis; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains
D001055:Apolipoproteins B; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL