“…However, guinea pigs and dogs which share with humans a poor plgA clearance through the liver, have high concentrations of plgA in the thoracic duct lymph, like rats or mice [37], The location of the poly-Ig-R in hepatobiliary tissues remains the most strik ing difference between species with high and low hepatic clearance of IgA, respectively. Synthesis and plasma membrane location of the poly-Ig-R/SC has been unequivocally as signed to hepatocytes in rats, rabbits and mice [38], and the SC-mediated transfer of plgA through hepatocytes is analogous to that described in enterocytes [39], However, only biliary ductular cells have been shown to synthesize the poly-Ig-R in humans, dogs and guinea pigs [6,29,39]. We confirmed recently, using electron microscopy with immunostaining, that at the very beginning of intrahepatic bile ducts, the so-called 'Her ring duct', only the biliary side of the duct, lined with cholangiocytes, expressed SC: no imrnunostaining of SC could be obtained at the hepatic side of the duct, lined with hepa tocytes [Seilles et al, unpubl.…”