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FIG. 2. The spatial expression of b3 transcripts between stages 10.5 (early gastrula) and 20 (neural tube closure). (A) Controls. (H, I)
Strophanthidin treated. np, neural plate; nt, neural tube; som, somite; nc, notochord; yp, yolk plug. All transverse sections apart from A and
B, which were taken through the yolk plug with dorsal ectoderm at the top. In B, the yolk plug is just visible at the bottom of the panel.
In A, arrows indicate local dense expression in dorsal lip mesoderm. In G, arrow indicates position of future motor neuron that is already
expressing b3. Strophanthidin treatment does not induce cell death in the nervous system. (J, K) Sections through control (J) and
strophanthidin-treated (K) embryos at stage 26 that had been stained by the TUNEL procedure. In both embryos two TUNEL-positive cells
are present in the nervous system either dorsolaterally (J, control) or in the roof plate (K, strophanthidin treated). TUNEL-positive cells
arrowed. A, B, Bar 5 150 mm; E, F, H, I, bar 5 100 mm; C, D, G, bar 5 50 mm; J, K, bar 5 200 mm.
FIG. 3. Spatial expression of b3 after neural tube closure. (A) Control embryos at stage 25 (A), 30 (B, C), and 35 (D). In C, the arrows
indicate b3 expression in dorso-lateral regions of the otic vesicle (ov). In D, arrow indicates b3 in the retina. (E) Sibling embryo at stage 30
after treatment with strophanthidin between stages 14 and 20. Note that b3 is not expressed in any dorsal structure. (F, G, H, I) Comparison
between the expression pattern of b3 (F, H) and N-tubulin (G, I) in the spinal cord (F, G) and brain (H, I). Note that only N-tubulin is
expressed in Rohan Beard cells (arrowed F, G). nt, neural tube; nc, notochord; som, somite; ov, otic vesicle; fp, floor plate. Transverse
sections. Bar 5 100 mm. Note that the strophanthidin-treated embryo in E has hypertrophy in the brain and eyes and is substantially larger
in this region than its sibling, shown in C. |
