Ultrastructural distribution of choline acetyltransferase in the goldfish optic tectum.

The ultrastructural localization of choline acetyltransferase (ChAT) has been demonstrated in the goldfish optic tectum. The distribution of the enzyme activity was observed in the optic fibers and in many synaptic vesicles of optic terminals. Other fibers and only few neurons (small or medium sized) are ChAT positive in the SFGS and in the SGC. The results indicate the presence of intrinsic cholinergic circuits in the goldfish optic tectum, in addition to the cholinergic retinotectal neurotransmission.