The structure of the mediodorsal cerebral cortex in the lizard Agama agama: a Golgi study.

A Golgi analysis was made of the cell types present in the mediodorsal cerebral cortex of the lizard Agama agama. Mediodorsal cortex can be divided into two areas, small-celled mediodorsal cortex (sMDC) and large-celled mediodorsal cortex (lMDC). Both sMDC and lMDC are four-layered cortices: superficial plexiform layer, cellular layer, deep plexiform layer and fiber layer, lMDC partially overlaps dorsal cortex (medial superposition). Using characteristics of the dendrites and criteria of location, dendritic field shape and soma size, two classes of neurons can be distinguished in sMDC. The first class consists of two types of solitary cells present in the superficial and deep plexiform layers and in the fiber layer. The second class consists of six types of pyramidal-like candelabra cells, composing the cellular layer. In lMDC solitary cells are also present in the superficial and deep plexiform layers and in the fiber layer. Large pyramidal cells of one type lie in the cellular layer. In addition, neurons of the dorsal cortex and of the ventral cell plate of Unger lie in the medial superposition area of lMDC. Throughout the entire mediodorsal cortex, protoplasmic and fibrous astrocytes and ependymal tanycytes are found.