Stable programming for map orientation in fused eye fragments in Xenopus.

Compound eyes were formed in Xenopus embryos at stages 32/33 by fusion in the right orbit of (1) two right naso-ventral halves, (2) two right ventral halves, (3) two right temporo-ventral halves, (4) one right and one left naso-ventral half and (5) one right and one left temporo-ventral half. The contralateral visuotectal projections from the operated eyes later showed abnormalities reflecting the anatomical arrangement of the fused fragments. The experiments thus revealed considerable stability of the developmental programme leading to the later development of map orientation, in the face of operative disturbance of the types used.