CR-positive neurons are L5a excitatory pyramidal neurons. Cux1 is specifically expressed in the upper layer (L2/3 and L4) excitatory neurons (B). CR-positive neurons are located just below the Cux1-positive neurons (A, C, C), and no CR- and Cux1-positive neurons are observed (C, C). Ctip2 is strongly expressed in L5b excitatory neurons (D). CR-positive neurons are located above the Ctip2-positive L5b neurons (E, F, F), and no CR- and Ctip2-positive neurons are observed (F, F). The CR-positive neurons are located between the Cux1-positive L2-4 neurons and the Ctip2-positive L5b neurons within the region corresponding to L5a (C, F). Most of the CR-positive neurons are NeuroD2- and Foxp2-positive (G- L, arrows). Scale bar: 100?m.