Cellular events during invasion by tumor cells of chick embryo skin

Tumor cell invasion was studied using the 9-day chick embryo skin (CES). The invasion process was broken down into 4 sequential events: adhesion, penetration, proliferation and colonization. Tumor cells used in this study included cells from various human and canine solid tumors, tumor cell lines from human and animal origin and malignant effusions. Where samples permitted, the invasion in CES was compared with tumorigenicity in athymic nude mice and clonal growth in soft agar. The effects of 5-FU and vincristine on the component events of invasion in CES were studied at doses that inhibited 3H-thymidine labelling. The results suggest that DNA synthesis and invasion are independent properties of tumor cells with malignant potential.