Establishment of metastatic growth by Yoshida Ascites

Establishment of metastatic growth by Yoshida Ascites Hepatoma 7974 in the chick embryo liver has been studied with light and electron microscopy. Tumor cells lie as emboli within the sinusoids for the first 24 hr and then begin to divide and invade the parenchyma by 48 hr after inoculation. At this time, tumor cells are seen to extend pseudopodia beneath the endothelium, which in many instances is disrupted by the advancing tumor. There is a concurrent loss of tight junctions and epithelial organization of the tumor cell islands. By 72 hr after inoculation, tumor cells are well established in the parenchyma, in intimate contact with hepatic cells. The parenchymal cells, however, show no obvious ill effects of this host-parasite interaction.