An image analysis system for the quantification of invasion in vitro.

We have tested the value of a computer-assisted image analysis program for the quantitative study of invasion in vitro using experiments that were previously described semi-quantitatively. Mouse fibrosarcoma cell (MO4) aggregates were confronted with precultured fragments of embryonic chick heart in organ culture. Confronting pairs were fixed after 1, 2, 3 and 4 days, and processed for paraffin sectioning and immunostaining with an antiserum against chick heart. The image analysis system allowed separate quantification of two aspects of invasion, namely, occupation of the heart tissue by MO4 cells and degeneration of the invaded heart tissue. Complex combination of occupation and invasion added a qualitative aspect of invasion that has not been described previously and that revealed qualitative differences in invasion under various circumstances.