Low magnification photomicrographs of CB-immunostaining in neonatal (P1) IC (left panel, A–E) and adult IC (right panel, A′–E′). Each panel shows a caudal (top) to rostral (bottom) series of frontal sections. The dense banded staining (see arrows) in each section is confined to the CNIC. Other immunostaining in the superficial layers of the DCIC and periaqueductal gray matter includes dense neuropil and cellular staining. Scale bars=0.5 mm, left panel; 1 mm, right panel. The CNIC is outlined and the main subnuclei of the IC are labeled in frames A, A′ for reference.