Immunohistochemical staining of P450arom in the hippocampal formation of an adult male rat. (A) The coronal section of the whole hippocampal formation. (B) The CA1 region. (C) The CA1 stained with P450arom IgG preadsorbed with purified P450arom. (D) The CA3, where not only cell bodies but also processes of neurons are densely stained. so, stratum oriens; pcl, pyramidal cell layer; sr, stratum radiatum. (Scale bar, 800 μm for A and 120 μm for B–D.)