Conditional loss of Notch1 in the cerebellar primordium results in severe hypoplasia and loss of Purkinje cell precursors. (a, b) Sagittal whole mount view of E16.5 floxNotch1 (a) and En1-cre; floxNotch1 (b) brains. The arrows in (a, b) indicate the position of the cerebellum. (c-f) Sagittal cryosections of floxNotch1 (c, e) and En1-cre; floxNotch1 (d, f) cerebella stained by hematoxylin and eosin histochemistry (c, d) or by immunohistochemistry for calbindin (e, f). Boxes in (c, d) indicate the approximate photographic fields in (e, f). Dashed box in (f) delineates the residual cerebellum in the mutant embryo. Scale bars in (e, f) represent 300 μm.