Effects of vitamin A administration upon Ito's fat-storing cells of the liver in the carp.

In the normal carp livers, Ito cells (fat-storing cells) could be identified with light and electron microscope within the hepatic sinusoidal wall and actually in the Disse's space, but they were almost lacking lipid droplets in the cytoplasm (empty Ito cells) in contrast to the majority of vertebrate species. After administration of large doses of vitamin A, fat droplets appeared in hypertrophic cytoplasm of enlarged Ito cells, and their size and number increased roughly in proportion to the amounts of vitamin A administered. This evidence was thought to demonstrate that the administration of large doses of vitamin A could convert empty Ito cells into lipid containing ones and further suggested that excess vitamin A administered might be stored in newly prepared lipid droplets of the Ito cells of the liver. In experimentally hypervitaminotic carp, hypertrophic Ito cells showed proliferation of fine filaments in addition to the accumulation of lipid droplets. The correlation between perisinusoidal fibrogenesis in the hepatic lobule and proliferation of cytoplasmic filaments in the Ito cells was discussed.