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Abstract

We examined the liver of adult polar bears, arctic foxes, and rats by gold chloride staining, fluorescence microscopy for the detection of autofluorescence of vitamin A, hematoxylin-eosin staining, staining with Masson's trichrome, Ishii and Ishii's silver impregnation, and transmission electron microscopical morphometry. The liver lobules of the arctic animals showed a zonal gradient in the storage of vitamin A. The density (i.e., cell number per area) of hepatic stellate cells was essentially the same among the zones. These results indicate that the hepatic stellate cells of the polar bears and arctic foxes possess heterogeneity of vitamin A-storing capacity in their liver lobules.

Hepatic stellate cells – from past till present: morphology, human markers, human cell lines, behavior in normal and liver pathology

“…In conditions of low dietary retinoid intake, the number and size of lipid droplets decrease, in order to ensure tissue retinoid needs [ 2 , 30 ]. Also, several studies reported important differences between the species, regarding the number of Ito cells localized in the liver and the number and size of lipid droplets contained in their cytoplasm [ 2 , 31 , 103 , 104 ]. According to these findings, HSCs lipid droplets are considered specialized organelles involved in the storage of retinoids [ 30 , 104 ].…”

Chemistry of the Retinoid (Visual) Cycle

“…But, it was Wald who discovered that retinol derivatives constitute the chemical basis of our vision, a contribution subsequently recognized by a Nobel Prize award in 1967. In 1950–1960, a variety of vitamin A metabolic transformations, including oxidation/reduction and esterification, were elucidated by Olson, − Goodman, − Chytil and Ong, − and Norum and Blomhoff. − The discovery that one set of these metabolites, namely retinoic acids, plays a key role in the nuclear regulation of a large number of genes added a notable dimension to our knowledge of gene expression. This mechanism is also a critical player in the successful healing of corneal wounds, a second manifestation of vitamin A-deficiency recognized earlier.…”