Figure 5

Developmental expression profile of QR1 in the chick embryo. (A-D) show RNA in situ hybridisation against QR1 of whole embryos at different developmental stages. (E-L) are coronal sections except for (H), a horizontal section. The plane of the sections is indicated in (A) and (D). (A) At HH 8 QR1 mRNA is detected in the entire brain region up to the boundary with the spinal cord (arrowheads). Coronal sections through HH8 show a diffuse expression of QR1 in the lateral neural tube of the brain (E) but no expression in the spinal cord (F). This expression pattern is also observed at HH 10 (B) and HH 12 (B). However, at stage 10 the expression is more intense medio-laterally (see fig. 3C). (D-I) At HH 20, QR1 mRNA is also present in spinal cord, lens and retina but no longer in the more anterior regions of the brain. A coronal section through the midbrain (G) at HH 20 shows QR1 expression in the ventral part. An horizontal section through the hindbrain (H) reveals QR1 expression also in ventral regions adjacent to the floor plate. Coronal sections through the spinal cord at HH stage 20 show a medial expression (J, K) and at hind limb level (K) an additional diffuse ventral expression. In the tail region of the spinal cord (L) QR1 expression is not detected. Scale bars are 50 μm.