Figure 2. Representative dark-adapted and light-adapted electroretinogram recordings from a control chick and an rge (mutant) chicken aged 270 days

The control bird ERG intensity series are typical for an adult chicken and show greater amplitudes than those recorded from the 7-day-old control bird. The 270-day-old control bird's dark-adapted and light-adapted thresholds were lower than that seen in the 7-day-old control chick (Compare with Figure 1). The dark-adapted and light-adapted ERG thresholds of the rge bird were greater than that of the control and greater than that of the 7-day-old rge chick (See Figure 1). The shape of the ERG waveform of the 270-day-old rge bird was similar to that of the 7-day-old rge chick, although the amplitudes were lower, the implicit times increased, and the b-wave was no longer supernormal. The light-adapted and dark-adapted responses of the 270-day-old rge bird were similar. Flash intensities from top to bottom were as follows: -2.4, -2.0, -1.42, -1.19, -0.79, -0.39, 0.00, 0.39, 0.85, 1.4, 2.3, 2.9 log cdS/m². Vertical bar represents 100 μV; X-axis is time in mSec.