Cyto-architecture and neuronal types of the dorsomedial cerebral cortex of the common Indian wall lizard, Hemidactylus flaviviridis

Abstract

The cyto-architecture and morphology of the neuronal types of the dorsomedial cortex of the lizard, Hemidactylus flaviviridis has been studied with the help of Cresyl violet staining and Golgi impregnation method. The dorsomedial cerebral cortex displayed three neuronal layers. Layer-I contains only few neuronal somas and also the dendrites ascending from the subjacent layers. Layer-II is characterized by two to three cell thick densely packed neuronal somas. Layer-III contains loosely packed neuronal somas and the dendrites and axon descending from layer-I and II. Below the layer-III an ependymal layer is observed just above the ventricle. Six classes of neurons were distinguished in the cellular layer of dorsomedial cortex of Hemidactylus flaviviridis: bitufted neurons, pyramidal neurons, inverted pyramidal neurons, bipyramidal neurons, multipolar neurons, and candelabra-like monotufted neurons. The pyramidal cells were large showing more or less single type present in the cellular layer. The multipolar neurons have mostly intracortical dendritic branching and connections. Bipyramidal neurons showed pyramidal appearance of their soma and send dendritic branches towards the superficial plexiform layer and deep plexiform layer. The candelabra-like monotufted neurons have very high dendritic branching. The comparison of the neuronal types of dorsomedial cortex of reptiles with the parahippocampal area of birds and CA3 region of mammalian hippocampus suggests possibility of their homology.