Fibrin precursors in early stages of metastases.

A suspension of Chang's hepatoma cells was inoculated into the tail vein of rats. Rats were killed at different intervals ranging from 30 seconds to 3 hours. Peroxidase-labelled goat anti-rabbit gamma globulin was applied to the tissue by an indirect method. Peroxidase-positive material was always found between the tumor cell and the endothelial lining and at the center of the ‘platelet tail’ as early as 30 seconds. Polymerized fibrin fibers first appeared at 15 minutes and more at 30 minutes. It is suggested that fibrin precursors act as a ‘glue’ for the tumor cell arrest.