Regeneration of the retinotectal system in a flatfish, Scophthalmus maximus L

Regenerating retinotectal fibres were visualized by radioautography in turbots (Scophthalmus maximus L.) maintained at 10 degrees-14 degrees C either after crushing one optic nerve or after crushing one nerve and removing the contralateral eye. Regeneration was found to be more extensive 2 days after crushing the right optic nerve than after crushing the left and was further enhanced by contralateral enucleation. The difference between experimental groups was markedly less pronounced by 113 days postoperatively and by 293 days the specimens resembled normal material. Between 113 and 222 days, a transient projection to the ipsilateral tectum was found, which disappeared by 293 days whether or not the contralateral eye had been removed. The differences between the present results and previous findings in symmetrical Cyprinid fish are discussed.