The development of the retinotectal projections from compound eyes in Xenopus

The retinotectal projections from double-nasal (NN), double-temporal (TT) and double-ventral (VV) compound eyes in Xenopus were studied autoradiographically and electrophysiologically during development. Early TT projections were confined to rostrolateral tectum and spread with advancing age to cover most of the tectum by shortly after metamorphosis. Early VV projections showed a decreased density of label on lateral tectum. Early NN projections appeared to extend across the entire rostrocaudal length of the available tectum at all stages of development, but showed a decrease in label density on rostral tectum. The results are discussed in relation to various hypotheses about the formation of retinotectal connexions.