[Response of omental milk spots to colloidal saccharated ferric oxide in the mouse: light and electron microscopic study (author's transl)].

In adult dd-mice, response of omental milk spots to colloidal saccharated ferric oxide intraperitoneally injected was observed by light and electron microscopy. Macrophages in milk spots and the fat tissue along the omental vessels took up large amounts of iron particles 1 hr after injection. Lymphoid cells in milk spots also could take up iron particles, though in very small amounts. At 2 hrs, milk spots were obscure in structure owing to remarkable infiltration of granulocytes. At 12 hrs, mononuclear cells appeared to be accumulated around blood vessels in the superficial zone of the fat tissue. Thus new milk spots appeared to be formed again. At 1 day, macrophages started to appear within formed milk spots. These cells had the ability to take up iron particles, and histochemically showed acid phosphatase activity. In addition, they were accumulated in thick layers along the surface of the fat tissue and milk spots 4 days after injection, but they then became gradually less in density with advancing time. Macrophages in the fat tissue, which could be distinguished from the ones in milk spots by remarkable HRP uptake, disappeared during the first 12 hrs after injection, but they appeared again along vessels in the fat tissue 1 day after injection. The response of two types of macrophages in omentum to colloidal iron was particularly discussed in detail.