The drainage and decrease of so-called intravenous fat pigment (i.v. fat pigment), which was a lipoid-pigment complex and deposited in the reticuloendothelial system after repeated infusions of Intrafat (intravenous fat emulsion), was observed in the liver of the rabbit by histological, histochemical and electron microscopic methods.
As a result, the i.v. fat pigment was mainly found in Kupffer cells immediately after the repeated injections of Intrafat. After then, depending on the period when no injection were given, it decreased gradually and disappeared finally from Kupffer cells. On the other hand, in the interstitium of Glisson s sheath, many phagocytes, extremely swollen and laden with i.v. fat pigment, appeared during the postinfusion period. Furthermore, these phagocytes laden with i.v. fat pigment were found in Glisson’s sheath for a long period, although they showed a tendency of decrease Histochemical and electron microscopic characteristics, quite similar to those of Kupffer cells, suggested that these phagocytes corresponded to the extremely swollen histiocytes or macrophages having some role in the drainage or the metabolism of the i.v. fat pigment.