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Fig. 5. Localization of En-2 protein in anterior structures and in the whole-mount brain. (A) Expression of En-2 protein in the mandibular arch of a stage 23 embryo. Arrows point to the nuclear staining. (B) Plane of frontal sections of stage 23 and 28 embryos shown in C, D and E. (C) Frontal section of the embryo shown in A; arrows point to the nuclei expressing En-2 in the presumptive mandibular arch. (D) Frontal section of a stage 28 tailbud (differential interference contrast optics) to show pharyngeal structures. MA=Mandibular arch, PPl=Pharyngeal pouch 1 and PP2=Pharyngeal pouch 2. (E) Same section as D (bright-field optics). Arrow indicate the nuclear staining in the mandibular arch. (F) Dissected brain from a stage 35/36 tadpole stained with mAb 4D9. The two boxes delineate the optic tectum shown in G and the pituitary shown in I. (G) Expression of En-2 in the optic tectum. The arrow points to the 'salt and pepper' like expression in the midbrain. (H) Whole-mount brain from a stage 35/36 embryo with HRP-stained retinal axons. The optic fibers are seen to terminate in the optic tectum (t), of the midbrain (mb). (I) Expression of En-2 in the region of the pituitary. The arrow points to the nuclear staining. The major area of the brain are indicated, t=optic tectum, p=Pineal, ot=optic tract, tel=Telencephalon, di=Diencephalon, mb=Midbrain, hb=Hindbrain. |
