In our study we used an osteoblast-like cell line (MC3T3-E1) to investigate influence and interaction of the individual components of the "Schulte coagulum" (venous blood, penicillin G, thrombin, gelatine sponge) upon cell proliferation. The autologous blood coagulum contains a high concentration of thrombin, the strongest physiological platelet activator. In order to be able to investigate the mitogenic influence of activated thrombocytes, we isolated human platelets by two different preparation techniques and stimulated MC3T3-E1-cells with the platelets’ supernatants. Compared to the control, thrombin trebled the proliferation of MC3T3-E1 in a bell-shaped dependence with a maximum at 10 U/ml. Penicillin G, which is added to the "Schulte coagulum" to prevent infections, inhibits proliferation at and above concentrations of 10,000 E/ml. This effect can be compensated by thrombin partly. The supernatants of denaturated gelatine sponge did not show any influence but increased with whole blood coagulum proliferation after 30 minutes. Stimulation with supernatants of human thrombocytes showed a strongly positive proliferation effect up to four times compared to the control. We then continued to determine which components of platelet granules would be able to influence proliferation. PDGF BB lead to an increase of up to five times compared to the control. Thromboxan-A2 inhibited proliferation in dependence from concentration. In our cell culture model, thrombin plays a central role in the stimulation of proliferation since it stimulates the MC3T3-E1 cells directly as well as indirectly by releasing further mitogenic substances from the thrombocytes.