[Colonization of the mouse liver by transplanted virogenic leukemia cells. Electron microscopic investigations (author's transl)].

Cells of a virogenic, immature myelogenic leukemia were injected in i.p. in one week old mice, strain NMRI, each animal receiving 10(5), 10(6) or 13(7) cells respectively in 0.2 ml Hanks' BSS. Mice were sacrificed at different times between 10 hrs and 21 days p.i. and liver specimens were prepared for electronmicroscopic studies. 10 hrs p.i. the leukemic cells are found in the sinusoids of the liver and after 30 hrs in the periportal fields. The leukemia cells migrate into the Disse spaces from the sinusoids. The leukemic cells penetrate with cytoplasmic digitations between connected endothelial cells. There is no lytic disintegration of the endothelial cells. The leukemic cells multiply by mitotic division of the Disse spaces, thereby compressing the liver cells. The cell membranes of both cell-types remain intact. Electronmicroscopically no evidence is found of a secretion of enzymes from the leukemia cells that destroy liver cells. Destruction of the liver cells is the consequence of the growth-pressure exerted by the dividing leukemic cells. Within the liver of the recipients the leukemic cells produce RNA-viruses. In the cytoplasm - frequently in the area of the Golgi-field - groups of immature A-particles are formed. In the virus fields the ribosomes disappear. The immature A-particles consist of two concentric electron dense shells. On the surface of the liver cells budding particles and immature C-particles develop. Extracellular mature C-particles with a homogeneous nucleoid and an irregular outer shell may be seen. The formation of viruses is found to be independent of the stage of the leukemia.