Brodmann area 20 is a subdivision of the cerebral cortex of the
guenon defined on the basis of
cytoarchitecture. It is cytoarchitecturally
homologous to the inferior temporal area 20 of the human (Brodmann-1909). Distinctive features (Brodmann-1905): area 20 is similar to
area 19 of Brodmann-1909 in the relative abundance of small cell types relative to the number of larger
pyramidal cells; a very dense, wide internal
granular layer (IV) composed almost exclusively of
granule cells, as in
area 18 of Brodmann-1909; a broad, clear internal
pyramidal layer (V) with few cells; and a distinct
multiform layer (VI). The major differences from areas 18 and 19 are somewhat lesser cell density; absence of a division of the external pyramidal layer (III) into sublayers 3a and 3b; layer V is more clearly distinguished from layer VI and, on average, has a greater density of pyramidal
ganglion cells than in the other areas; layer VI is wider, more diffuse and has fewer cells that are concentrated in the outer part of the layer to produce a denser sublayer 6a and a less dense sublayer 6b. ==See also==