Retino-tectal projections from half-ventral and half-dorsal eye rudiments in Xenopus

Abstract

When the ventral half of a developing eye in Xenopus larvae was removed at stage 32, the remaining fragment rounded up and developed into an eye which looked macroscopically normal by mid-larval stages. Eyes from half-dorsal rudiments were usually small, had more than one ventral fissure, and showed abnormal pupils. The contralateral retinotectal projection was always found to be normally ordered when mapped in later tadpole stages, or, just after metamorphosis. No mirror-image duplicated maps were seen, as was found previously in eyes deriving from half-nasal and half-temporal rudiments. It is concluded that the 'rule of distal transformation' does not apply to eyes which are generated from embryonic rudiments.