EYE PRIMORDIUM TRANSPLANTATION IN XENOPUS EMBRYO

A part of the eye primordium, the presumptive retinal anlage, was tran splanted from stage-23/24 Xenopus borealis to replace the removed olfa ctory anlage of Xenopus laevis. Cells of the two species can be distin guished under fluorescence microscopy, and we used the resulting chime ras to determine whether the transplanted eye primordium would inhibit the regeneration of the olfactory anlage, whether it would connect wi th its usual target, the diencephalon, and whether migration of cells would occur from the transplant to the host CNS or from the host CNS t o the transplant. In all cases, the olfactory anlage regenerated promp tly, and normal olfactory bulbs developed. Omission of the eye stalk i n the transplant resulted in failure of an optic nerve to develop from the developing retina. A cellular bridge containing the optic axons c onnected the transplanted retina to the diencephalon. Cells from the t ransplant migrated freely through the cellular bridge to several CNS r egions. Their morphology, topographic arrangement, number, and relatio ns with other host elements are consistent with the hypothesis that th ese cells belong to both glia and neuron types.