[Neuronal organization of the dorsoventral ridge of the reptilian forebrain]

Cytoarchitectonics and neuronal structure of the dorsoventricular ridge (DvR) of the forebrain in two species of the squamous reptiles--Agama caucasia L. and Agama sanguinolenta L.--were investigated by means of certain neurohistological methods. In the middle part of the Agama hemisphere the DvR has two regions: medial parvocellular and lateral magnocellular, each of them being presented by two cellular zones--the subependymal zone and core nucleus. Three main types of neurons are described: multipolar spinose neurons, multipolar aspinose neurons and subependymal neurons. The multipolar spinose neurons form the base of the DvR neuronal structure and, according to the structure of the dendritic tree, can be divided into three types: those having loose branching, those having dense branching and piriform ones. Quantitative analysis demonstrates a statistically significant difference in a number of parameters in the dendritic tree having neurons with loose branching and dense branching. Vast axonal plexuses formed by axons of the multipolar spinose and aspinose neurons and the ramifide system of afferent and efferent fibres are noted.