Abstract:
To broaden our insight into the organization of the basal ganglia of amphibians, the development of the connections of the striatum and the nucleus accumbens was studied by means of tract-tracing techniques based on the transport of biotinylated dextran amines. In a number of experiments, these techniques were combined with tyrosine hydroxylase immunohistochemistry to identify the sources of catecholaminergic inputs to the striatum and the nucleus accumbens. Already at late embryonic stages, the basal telencephalon receives inputs from cells located in the amygdala, the thalamus, the suprachiasmatic nucleus, the raphe nucleus, and the rhombencephalic reticular formation. At these stages, the rostral part of the posterior tubercle seems to be the only source of the dopaminergic input to the basal telencephalon. During premetamorphosis, not only a differentiation between connections of the striatum and the nucleus accumbens could be made, but new sources of inputs were also detected in the mesencephalic and isthmic tegmentum, the parabrachial nucleus, and the nucleus of the solitary tract. Double-labeling experiments revealed that, at these stages, in addition to the posterior tubercle, cells withi...