Electron microscopic studies on multinucleate foreign body giant cells derived from Kupffer cells in mice given Indian ink intravenously.

Changes in Kupffer cells in mice given intravenous Indian ink were studied with the electron microscope. Kupffer cells as well as hepatic sinusoidal endothelial cells take up Indian ink particles by pinocytosis. In addition, a few Ito cells and hepatocytes ingest a small number of particles. The carbon particles are stored in cytoplasmic vacuoles in all these cell types. Aggregates of Kupffer cells containing many vacuoles stuffed with carbon particles are seen in the sinusoidal lumen, Disse space and interlobular connective tissue space 3 and 4 days after injection with Indian ink. One month after the injection, large clumps of aggregated Kupffer cells containing numerous carbon-filled vacuoles are distributed in the Disse space and other connective tissue spaces. The Kupffer cells in these clumps are in close contact and are partly fused with one another. After 3, 4 and 6 months, large multinucleate foreign body giant cells with numerous large vacuoles containing densely-packed ink particles are seen throughout the liver tissue. They are considered to be formed by fusion of Kupffer cells. Some endothelial cells also store ink particles in cytoplasmic vacuoles for as long as 6 months after injection.