Immunohistochemistry of vacuoles occurring in rat hepatocytes after retinol administration

The vacuoles occurring in rat hepatocytes after intraportal injection of retinol (33 or 67 micrograms) were examined immunohistochemically using respective antibodies against rat albumin, human retinol-binding protein, human ceruloplasmin, human alpha 1-antitrypsin, human transferrin, and human prealbumin as representative plasma proteins. The occurrence of the vacuoles reached a numerical maximum 30 min after injection of 67 micrograms retinol, followed by a temporal decrease. Hepatocytes from control rats, which had been intraportally injected with either blood plasma diluted to 2/3 concentration or with retinol palmitate solvent (castor oil) dissolved in blood plasma, showed immunoreactive fine granules without the occurrence of vacuoles in the cytoplasm. Identical vacuoles in serial sections appeared immunohistochemically either immunoreactive or non-immunoreactive for all the antibodies used, with rare exceptions. The occurrence of several rare exceptions suggested that 2 kinds of vacuoles might be formed in different cytoplasmic compartments. A zonal distribution of vacuoles was apparent in the hepatic laminae (or acini) within the liver lobules. The vacuoles were predominantly distributed in zone 2, and to a lesser extent in zone 3 and zone 1 in that order.