Light-dependent development and asymmetry of visual projections.

The projections from thalamus to visual Wulst in chicks are asymmetrical and their development is determined by exposure to light just before and after hatching. The asymmetry results from the orientation of the embryo in the egg, the left eye being occluded and not the right. We have shown that this asymmetry can be eliminated by incubating the embryos in darkness or light so that both eyes receive the same stimulation.