Figure 5. General features of cortical immature neurons are highly preserved in mammals whereas their amount is greater in large-brained species.
(A) Some aspects, including morphology, cell types, degree of immaturity and non-proliferative activity (left), appear quite constant across the mammalian species, whereas their extension in the neocortex (middle) and their overall amount (right) vary remarkably, increasing from small, lissencephalic to large, gyrencephalic brains. On the right, the estimation of total number of cINs in mouse and chimpanzee calculated by multiplying the median number of DCX+ cells in the neocortical layer II for the number of cryostat sections cut from the entire hemispheres; Supplementary file 4). (B) Principal Component Analysis (PCA; the different species are arranged according their orders; see text). The animal species are identified by different colours and abbreviations: CYA for Cat Young-Adult, CMA for Cat Middle Age, SYA for Sheep Young-Adult, SMA for Sheep Middle Age, PYA for Primates Young-Adult Chimpanzee, PS for Primate (Senior) aged Chimpanzee. (C) Map of character evolution on the phylogenetic tree illustrating the independent emergence of neocortical DCX+ neuron densities in the mammalian species considered. (D) PGLS regression showing that linear density of neocortical DCX+ neurons covaries significantly with brain weight and layer II perimeter.
Figure 5—figure supplement 1. PGLS regression analysis between layer II DCX+ neuron density and gyrification index.
