Transverse section through the cerebrum of the forebrain (Luxol Blue & Hematoxylin stain). The cerebrum features deep gray matter called nuclei (asterisks), white matter (wm), and superficial gray matter called cerebral cortex. The cerebral surface is thrown into ridges and grooves, respectively called gyri (G) and sulci (arrows). Also labeled are: corpus callosum (cc) and optic nerves (opt).