Fig. 5. Microinjection in slugs. (A) Subtracted image of a slug showing two wave fronts (arrows), the position of the microelectrode containing 10^-2 M cAMP is indicated. (B) The waves have disappeared after the cAMP pulse, the microelectrode had been removed after the injection. (C) Time-space plot showing the disappearance of the waves after cAMP injection. The arrow indicates the position of micro-pipette and the time of the injection. (D) Brightfield image of a slug with an inserted micro-electrode (outline) containing phosphodiesterase (5 mg/ml). (E) Subtracted image of the same slug. The arrows point at two wave fronts coming from the slug tip. (F) Time-space plot. The waves stop around the injection site. The arrow indicates where and when the micro-pipette was inserted. Scale bars: 100 µm.