Pax5-expressing progenitors predominantly contribute to midbrain and cerebellar development. (A) HC expression in an adult Pax5^Cre/+Rosa26^invHC/+ brain, analyzed by immunofluorescence staining of coronal sections sampled at regular intervals along the posterior–anterior axis of the brain. Left: mCherry expression (red) with DAPI staining (blue). Right: A mirror image showing mCherry expression in gray. White dotted lines outline the circumference of the sections. The different sections were taken from the brain locations indicated by their reference to the Bregma landmark shown in the top right corner. The scale bar denotes 2 mm. CB, cerebellum; CH, cerebrum; IB, interbrain; MB, midbrain; MY, medulla oblongata of myelencephalon; P, pons. (B) Lineage-tracing analysis of cerebellar cell types. Top: Sagittal section of an adult Pax5^Cre/+Rosa26^invHC/+ brain indicating HC reporter protein expression (red) in the entire cerebellum (left) or indicated insert (right). Middle: Anti-calbindin (blue), anti-parvalbumin (green), or anti–GABAA-R6α (cyan) staining is shown together with a merged image. The indicated inserts contain Purkinje cells (I), interneurons (II), or granule cells (III). Bottom: Individual antibody staining and mCherry expression together with a merged image of insets I–III. Scale bars: 1 mm (overview); 50 μm (middle); 10 μm (I–III). (C) smRNA-FISH analysis of the SN and VTA midbrain regions on coronal sections of an adult Pax5^Cre/+Rosa26^invHC/+ brain, analyzed with probes for Gad1/Gad2 (green), mCherry (red), and Pax5 (white) in combination with DAPI (blue). The scale bar denotes 5 μm. The data (A–C) are representative of three independent experiments.