Ultrastructural evidence for the presence of ferritin-iron in the biliary system of patients with iron overload.

Ferritin-like particles were observed in bile canaliculi of patients with iron overload. These particles have been further investigated by: a staining method enhancing the size and contrast of ferritin protein, and electron probe microanalysis detecting the presence of the elements iron and phosphorus. Morphological observation of coated vesicles in the cytoplasm adjacent to the bile canaliculi and coated pits in the canalicular membrane suggests a transport mechanism via membrane-bound organelles. Support is given to the theory that part of the iron, stored in the liver, leaves the hepatocyte by excretion of ferritin into the bile.