Nuclear deviation in hepatic parenchymal cells on sinusoidal surfaces in arctic animals

In normal rat and human, most of the nuclei of hepatic parenchymal cells ar e centrally located in the cytoplasm, However, it is reported that the nucl ei of hepatic parenchymal cells are situated at a deviated position on sinu soidal surfaces under pathological situations such as chronic hepatitis, he patocellular carcinoma, adenomatous hyperplasia, or regeneration. During a study on the mechanism of extreme vitamin A-accumulation in hepatic stellat e cells of arctic animals including polar bears, arctic foxes, bearded seal s, and glaucous gulls, we noticed that these arctic animals displayed the n uclear deviation in hepatic parenchymal cells on sinusoidal surfaces. In th is study, we assessed the frequency of hepatic parenchymal cells showing th e nuclear deviation on the sinusoidal surfaces in arctic animals, A signifi cantly higher frequency of the nuclear deviation in hepatic parenchymal cel ls was seen in polar bears (89.8 +/-3.4%), arctic foxes (68.6 +/- 10.5%), b earded seals (63.6 +/-8.4%), and glaucous gulls (24.2 +/-5.8%), as compared to that of control rat liver (9.8 +/-3.5%). However, no pathological abnor mality such as fibrosis or necrosis was observed in hepatic parenchymal and nonparenchymal cells of arctic animals, and there were no differences in t he intralobular distribution of parenchymal cells displaying the nuclear de viation in the livers from either arctic animals and control rats. The hepa tic sinusoidal littoral cells such as stellate cells or extracellular matri x components in the perisinusoidal spaces may influence the nuclear positio ning and hence the polarity and intrinsic physiological function of parench ymal cells.