Whole Mount and Tissue Section Imaging

For whole mount images, mouse embryos were dissected and cerebella were washed thoroughly in 1 x PBS and photographed with a Zeiss Stemi 2000-C dissecting microscope. For tissue sections, mouse embryos or dissected tissues were fixed in fresh 4% (w/v) para-formaldehyde and embedded in paraffin wax. Thin sections (4μm) were cut onto “Superfrost Plus” slides (VWR International Ltd.) and deparaffinised and rehydrated by standard methods. Sections were stained with haematoxylin and eosin (BDH Chemicals Ltd.) for 2 min, then dehydrated in ethanol, cleared in xylene and mounted in DPX. For immunohistochemistry, epitope recovery was obtained by boiling in 1 mM EDTA pH8.0 for 2 min using a pressure cooker, followed by 30 min cooling. Blocking and application of primary antibodies was as described^{28 (link),32 (link)}. Appropriate HRP-conjugated secondary antibodies (Dako Inc.) were used (final dilutions of x10000-25000). Sections were developed in “Sigma Fast” 3,3′-diaminobenzidine (DAB) with CoCl₂ enhancer and counterstained with Mayer’s haematoxylin (Sigma-Aldrich Co. Ltd.).