An in Vitro Quantitative Assay for Tumor Cell Invasion1

An in vitro quantitative assay of tumor cell invasion is described. The assay measures the rate at which [12sl]iododeoxyuridine-labeledtumor cells migrate through the chorioallantoic membrane of developing chicken em bryos. Invasion chambers were prepared from amber latex cylinders, chorioallantoic membrane, and thread liga tures. The chambers were placed in glass vials to rest on discs of photographic sponge immersed in tissue culture medium. Labeled tumor cells were added to the chamber, and the vial was incubated at 37°. At various time points individual chambers were monitored to determine the number of viable, labeled cells that had passed through the membrane and were present in the medium, on the glass vial, or in the sponge. The application of the assay may be of use in delineat ing the mechanisms of tumor cell invasion.