Increase in synaptic sites in goldfish tectum after partial tectal ablation

In young goldfish after partial ablation of the tectum, the number of synaptic contacts and terminals in a column through the stratum fibrosum et griseum superficiale of the tectum was increased to an extent corresponding to the greater input of optic axons projecting to the remaining tectum. This finding is consistent with previous results based on counting degenerating optic terminals, and therefore establishes that the optic axons make approximately normal numbers of terminals in the remaining tectum. The conflict between this finding and results obtained on older fish suggests that tectal cells of younger fish can more readily accept an increased number of optic terminals.