The term area 10 of Brodmann (guenon) refers to a subdivision of the frontal lobe of the guenon defined on the basis of cytoarchitecture. Brodmann-1909 did not regard it as cytoarchitecturally homologous to his area 10 of Brodmann (human). Distinctive features ( Brodmann-1905 ): compared to area 9 of Brodmann (guenon), the multiform layer (VI) of area 10 shows an unusual organization of cells into trains oriented parallel to the cortical surface that are separated from one another by narrow cell-free fiber bundles; less marked differences are an overall thinner cortical thickness and a somewhat thicker molecular layer of the cerebellar cortex (I). Compared to area 6 of Brodmann (guenon), area 10 has a subtle but clearly present internal granular layer (IV); layer 3b of the of the external pyramidal layer (III) is weakly developed and composed of medium sized pyramidal cells; and the internal pyramidal layer (V) is more developed.