The Golgi architecture of the domestic chick archistriatum.

Investigation of the chick archistriatum revealed that it was not possible to distinguish distinct sub-regions on the basis of their Golgi architecture, despite the fact that the pigeon archistriatum has been suggested to comprise "amygdaloid" and "sensorimotor" divisions. Nine sub-types of projection neuron and four of local circuit neuron were identified in the chick archistriatum. Projection neurons were generally larger with thicker dendrites than those in other regions of the chick telencephalon. A greater proportion of these projection neurons also had highly densely spiny dendrites. These findings suggest that archistriatal neurons receive a large, possibly complex afferentation and project considerable distances. Large and medium-sized local circuit neurons with varicose axon branches and relatively large neurogliaform cells were characteristic of the archistriatum. All types of archistriatal neuron were identified in both 28 and one day old chicks. However, presumptive highly densely spiny projection neurons appeared relatively immature in the one day old chick archistriatum.