Quantitative light microscopic study on the distribution of Kupffer cells during chemical hepatocarcinogenesis in the rat

The quantitative distribution of Kupffer cells was measured in the liver of Fischer-344 male rats during the course of chemical hepatocarcinogenesis according to the Solt — Farber model, i.e. an initiating agent, a selective mitogenic inhibitor and a strong proliferation stimulus were applied subsequently. Pre-neoplastic and neoplastic lesions were followed up to 17 months. Kupffer cells were detected by the phagocyted car-rageenan stained with toluidine blue and were counted using the ocular square in the light microscope. In the non-transformed areas of the liver of treated rats the number of Kupffer cells was generally different from the values of untreated controls. The altered cell foci contained fewer Kupffer cells than the normal untreated rats and the non-transformed liver areas, while in hepatocellular carcinomas there was a high reduction in the number of detectable Kupffer cells. The number of Kupffer cells was variable around and within neoplastic nodules. While Kupffer cells do not follow the neoplastic proliferation of hepatocytes during hepatocarcinogenesis, it is possible that humoral factors are produced by transformed hepatocytes against Kupffer cells.