Retinal projection to a rotated tectal reimplant following long-term tectal denervation in adult goldfish.

Following optic nerve crush, the precise termination sites of regenerating goldfish optic axons may be influenced by the presence or absence of degenerating axonal debris from the previous projection. We investigated wheter tectal polarity reversal can be induced in the absence of axonal debris. The right optic tectum was denervated by contralateral eye removal. One year later, when no debris was present, a piece of the right tectum was rotated and innervation by the right eye was induced by removal of the left tectum. The new ipsilateral projection to the rotated region was correspondingly rotated. It is concluded that retention of tectal polarity is not dependent upon degenerating axonal debris.