Cell types of the paleostriatal complex of the domestic chicken (Gallus domesticus): a Golgi study

A study of was carried out of Golgi impregnated material in two regions of the paleostriatal complex of the chick telencephalon, the lobus parolfactorius and paleostriatum augmentatum. As in our previous investigation of the chick medial hyperstriatum ventrale, two major classes of neurons were observed in the paleostriatum: a Golgi I type neuron (type 1) with long axon (putative projection neuron) and a Golgi II type neuron (type 2) with short axon (putative local circuit neuron). Based upon the nature of the axon (bifurcating or nonbifurcating, ascending or descending) and of the dendrites (spiny or aspinous, and thickness), the following subclasses (types) were identified: two projection and three local circuit neurons in the lobus parolfactorius and two projection and two local circuit neurons in the paleostriatum augmentatum. In addition to known differences in developmental chronology and extrinsic connectivity, the lobus parolfactorius clearly differs from palaeostriatum augmentatum in cellular composition and organization. From its cytoarchitectonic appearance we would suggest that the lobus parolfactorius is the paleostriatal region of greater complexity.