Fig. 4. The transformed retrosplenial cortex is composed of large hippocampus-like pyramidal neurons. (A,E-G) Golgi impregnation of wild-type (A) and Tg^S transgenic (E-G) posterior Rsc revealing a CA1-like morphology of pyramidal neurons. (B-D,H-J) Alterations in pyramidal neuron morphology in Tg^S transgenic (H-J) posterior Rsc compared with wild type (B-D) shown by fluorescent visualization of EGFP-labeled outer layer neurons at P14, following in vivo transfection with a pCIG2-EGFP expression vector at E15, in coronal sections counterstained with DAPI (B,H). Note that Rsc pyramidal neurons born after E15 in Tg^S transgenic brains are large cells that settle in a compact pyramidal cell layer (J), whereas these neurons are small outer-layer pyramids in wild-type brains (D).