Fig. 6. Microinjection of m⁷GDP inhibits the first mitotic division of sea urchin embryos. m⁷GDP was introduced by microinjection at a final intracellular concentration of 1 mM into unfertilized eggs. The control corresponds to non-injected eggs and buffer corresponds to eggs injected with the microinjection buffer. Cleavage was scored by observation under a light microscope at 150 minutes post-fertilization. An average of 60 unfertilized eggs were injected for each compound in each experiment, and error bars represent the standard deviation (± s.d.) of three independent experiments. Significance was assessed using Fisher's F-test and Student's t-test. ^*P<0.005, significant difference between eggs microinjected with m⁷GDP, microinjected with buffer and non-injected eggs.