Measurement of the ability of cells to infiltrate normal tissues in vitro.

Organ cultures of chorioallantoic membranes of hen eggs have been used to establish a quantitative method of measuring the infiltrative ability of a variety of normal and tumour cells. Normal fibroblasts, mouse peritoneal cells and cells of low tumorigenicity infiltrated poorly and slowly whereas most tumours infiltrated rapidly. Some cells of the more invasive tumours achieved minimum rates of migration through the normal tissue of 2-3 μm/h. One tumour line which tended to form aggregates on the chorioallantoic membrane elicited a pronounced rejection response from the ectoderm of the membrane. Colcemid, which inhibits the formation of cell processes and the directional migration of cells, and dibutyryl cyclic AMP, which restores certain aspects of normal behaviour to tumour cells in vitro, had little effect on the invasion of the membrane by tumour cells.