Fig. 4. RGC axons fail to exit the eye in Bmp7 null embryos. (A,B) The posterior view of the eye globes from E18.5 embryos shows the complete absence of the optic disc (open arrow in B) and the presence of hypopigmented streaks (arrowheads) in the Bmp7-null microphthalmic embryos when compared with wild-type littermates (arrow in A). (A',B') The images show cryostat sections of the same eyes immunostained with anti-neurofilament antibodies (red). The arrowheads in B' indicate the abnormal accumulation of fibres in the subretinal space. (C,D) Frontal cryostat sections from E14.5 wild-type (C) and Bmp7^-/- (D) optic cups were immunostained with antibodies against PAX2 (green) and Tuj1 (red). PAX2-postive cells are absent in the mutant and there is the aberrant fibre growth in the subretinal space or vitreal surface (arrowheads in D,D').