For histoblotting, animals were deeply anaesthetized by hypothermia (P0-P5) or by intraperitoneal injection of ketamine/xylazine 1 : 1 (0.1 mL/kg b.w.) and the brains were quickly frozen in liquid nitrogen. For immunohistochemistry, animals were anaesthetized and transcardially perfused with ice-cold fixative containing 4% paraformaldehyde and 15% (v/v) saturated picric acid (also containing 0.05% glutaraldehyde for electron microscopy) made up in 0.1 M phosphate buffer (pH 7.4). After perfusion, brains were removed and immersed in the same fixative for 2 h or overnight at 4 °C. Tissue blocks were washed thoroughly in 0.1 M phosphate buffer. Coronal 60-μm-thick sections were cut on a Vibratome (Leica V1000).
