In order to precisely delineate the core and the shell regions of the Acb, transverse sections adjacent to those used for stereology were immunostained for calbindin (CB). Briefly, the immunoperoxidase protocol described above was used but with a monoclonal primary antibody against CB (1/500, overnight at 4 oC, catalog no. C-9848, Sigma-Aldrich) and a biotinylated horse anti-mouse secondary antibody (1/200, 2 h at RT, catalog no. BA-2000; Vector Laboratories).
