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FIG. 2. Patterns of contactin mRNA expression in tailbud embryos, revealed by whole-mount in situ hybridization. (A and B) Lateral
views of the embryos at stage 24 (A) and stage 32 (B), with the anterior to the left. Weak contactin signals (arrowheads) are detectable in
the anterior spinal cord, the hindbrain, and the trigeminal nerves in (A). Intensity of the overall contactin signal increases and the areas of
expression expand by stage 32 (B). (C and D) Cross sections of the whole-mount hybridized stage 32 embryo at the levels of the midbrain
(C) and spinal cord (D). Contactin mRNA is detected in the trigeminal nerve (small arrowheads), the fasciculus longitudinalis medialis, and
the ventral fascicles (large arrowheads) in the midbrain section (C). It is also detectable in RB neurons (arrowheads), lateral fascicles (lf), and
ventral fascicles (vf) in the spinal cord section (D). hb, hindbrain; nc, notochord; sp, spinal cord; tgn, trigeminal nerve. Scale bars, 100 mm. |
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cntn1 (contactin 1) gene expression in Xenopus laevis embryo, assayed via in situ hybridization, NF stage 32, lateral view, anterior left, dorsal up. |
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FIG. 3. Distribution of contactin protein in stage 37/8 embryos, visualized by whole-mount immunocytochemistry. (A) A lateral view of
the anterior 2/3 of the stained embryo, showing nervous tissue-specific distribution of contactin immunoreactivity. (B) An enlarged dorsal
view of the brain portion of the embryo shown in (A). Axon tracts in the brain and primary olfactory region (arrowhead) are contactin
positive. (C, D, and G) Cross sections of the stained embryo at the levels of midbrain (C), hindbrain (D), and posterior spinal cord (G). Contactin is expressed in the postoptic commissure and the optic chiasm of the lateral diencephalon (arrowheads in C) and the fasciculus
longitudinalis medialis in the ventral marginal region (arrowheads in D). (E and F) Enlarged lateral (E) and dorsal (F) views of a part of the
embryos, showing contactin-positive dorsal and ventral spinal fascicles. An arrow and an arrowhead in (E) represent contactin-positive cell
bodies of a RB neuron and an EM neuron, respectively. (G) A pair of RB neurons (small arrows), an EM neuron with peripheral axon (large
arrow), and dorsal fascicles (arrowheads) are strongly contactin positive. ac, anterior commissure; dr, dorsal lateral tract; df, dorsal fascicle;
flm, fasciculus longitudinalis medialis; hb, hindbrain; mb, midbrain; nc, notochord; ov, otic vesicle; pc, posterior commissure; poc,
postoptic commissure; sp, spinal cord; tec, optic tectum; tgn, trigeminal nerve; vf, ventral fascicle. Scale bars, 100 mm (A–F); 200 mm (G). |
