Interaction between photoreceptors and pigment epithelium in developing pigeon retina: an electrophysiological and...

In pigeons as in other vertebrates, the electroretinogram (ERG) first can be recorded simultaneously with the appearance of the photosensitive lamellae in the developing outer segments. At around 4-6 days after the bird has hatched a small negative-positive complex (a-b-wave) appears. Simultaneously, a c-wave can be recorded and the termination of the stimulus is followed by a positive d-wave. The ERG amplitude progressively increases during the first month as the lamellar structures complete their maturation. The c-wave amplitude shows a steady increase in the early post-hatching period which parallels the a-b complex maturation. In newly hatched pigeons the retinal pigment epithelial (RPE) cell consists of a small soma and long villi which extend toward the photoreceptors. During maturation a progressive increase in RPE thickness and number of cytoplasmic elements can be observed.