Fig. 1. Expression analysis of BMPs in the developing cerebellum. In situ hybridisation was performed on vibratome sections of mouse and chick cerebellae with probes against Bmp2, Bmp4, Bmp7 and sonic hedgehog (Shh). (A) Hybridisation of a postnatal day 0 (P0) mouse with a Bmp2 probe shows expression in the EGL but weak expression in the IGL. (B,C) In a chick HH42 cerebellum, Bmp2 expression is weak in the EGL and strong in the IGL. (D) Double labelling with the Purkinje cell marker calbindin revealed that Bmp2 expression is located just beneath the Purkinje cell layer. (E) Hybridisation with a Bmp4 probe at HH38, shows expression in the EGL and weak expression in the IGL. (F,G) A similar pattern of Bmp4 expression is maintained throughout cerebellar development. (H) Hybridisation with a Bmp7 probe at HH38 reveals expression in migrating Purkinje cells. (I,J) Bmp7 expression is maintained in settled Purkinje neurones at HH42. (K) Hybridisation with a Shh probe at HH38 shows expression in migrating Purkinje cells. (L,M) Shh expression is maintained in settled Purkinje neurones at HH42.