Fig. 5.

Dose-dependent change in retinotectal topography with inhibition of NO synthesis. The graph shows the number of retrogradely labeled ganglion cells on the temporal side of E17 retinas after microspheres were microinjected into a small spot in the posterior region of the tecta contralateral to the retinas analyzed. Experimental embryos were treated daily from E9 to E16 with doses ofl-NAME as shown. Control embryos were treated withd-NAME, saline or were untreated. Another group of embryos was treated with 10 nmol of phenylephrine HCl to test the effect of vasoconstriction on refinement. The division between nasal and temporal retina was deemed to be the optic fissure and a line that extended from the optic fissure into the dorsal retina. This cut to divide the two sides of the retina was made before the retinas were removed from the sclera. The ★ indicates results significantly different from each of the controls (p < 0.001). Error bars indicate SE; n = 5 for each treatment group.