Transient projections from the fronto-parietal and temporal cortex to areas 17, 18 and 19 in the kitten.

Using the retrograde tracers, fast blue and horseradish peroxidase we have shown the presence of projections from extensive regions of the frontoparietal and temporal cortex to areas 17, 18 and 19 in the newborn kitten. These projections are transitory as they do not exist in the adult cat. The anterograde transport of horseradish peroxidase conjugated with wheat germ agglutinin after injections in frontoparietal and temporal cortex revealed that these transitory projections terminate in the gray matter and that they could therefore play a functional role in the development of the visual cortex.