Lack of axon regeneration of isthmic neurons in juvenile Xenopus.
In young adult Xenopus laevis frogs the axons of isthmic neurons projecting to the contralateral tectum were severed at the postoptic commissure and the survival of such neurons was studied between 2 and 26 weeks after the operation. Pyknotic neurons were first observed in the isthmic nucleus 2 weeks after axotomy. The continued neuron loss resulted in the decrease from 2920 in intact animals to 1520 surviving isthmic neurons in animals 26 weeks after the operation. These findings suggest that (i) severed axons of the isthmic neurons are not able to regenerate to their natural target, and (ii) isthmic neurons require continuous contact with appropriate tectal target for their survival.
McCart
R
R
Department of Anatomy and Histology, School of Medicine, Flinders University of South Australia, Adelaide.
Straznicky
C
C
D000818:Animals; D002452:Cell Count; D009416:Nerve Regeneration; D013477:Superior Colliculi / Q000166:cytology* / Q000502:physiology; D013997:Time Factors; D014795:Visual Pathways / Q000502:physiology*; D014982:Xenopus laevis / Q000502:physiology*