Ultrastructural study of liver sinusoids of mice during invasion by leukemic myelocytes.

Results of an ultrastructural study of liver of RF mice during invasion by leukemic myelocytes were reported. In early stages of infiltration, leukemia cells adhered to the endothelial cells of the sinusoidal wall; gaps 1-4 mu in diameter then developed in the endothelium, and leukemia cells passed through the gaps to enter the extravascular space. Other sinusoids became occluded by leukemic myelocytes, the endotheilium disintegrated, and the occluding cells thus became extravascular. In late stages of infiltration, when leukemia cells migrated back into the sinusoids, the endothelium was continuous and leukemia cells passed through temporary pores located within endothelial cells.