Fig. 4.

Size-reduced olfactory bulbs in adult β8^–/– mice. (A,B) P90 brains from wild-type (A) and β8^–/– (B) littermates that were killed and cardiac-perfused with Bouin's fixative. In comparison to the wild-type mouse (arrow in A), note the smaller olfactory bulbs in the β8^–/– animal (arrow in B). (C) Images of H&E-stained coronal sections through olfactory bulbs of P90 wild-type and β8^–/– mice. Note that β8^–/– olfactory bulbs are significantly smaller, but have an apparently normal cytoarchitecture. GLO, glomerular layer; EPL, external plexiform layer; MCL, mitral cell layer; IPL, internal plexiform layer; GCL, granule cell layer; RMS, rostral migratory stream. (D,E) Coronal sections through olfactory bulbs taken from P90 wild-type (D) and β8^–/– (E) mice were immunofluorescently labeled with anti-DCX (green) to visualize neuroblasts and differentiated neurons and anti-GFAP (red) to identify astrocytes. Note that fewer DCX⁺ neuroblasts (green) are present in the RMS of β8^–/– olfactory bulb than in the wild-type control (arrowheads in D,E). However, similar numbers of GFAP⁺ astrocytes (red) and differentiated neurons (green) are present in the olfactory bulbs of β8^–/– mice in comparison to wild-type control mice (arrows in D,E). RMS, rostral migratory stream; DCX, doublecortin; GFAP, glial fibrillary acidic protein.