Figure 2. miRNA expression in the nervous system. A: Transverse section at caudal hindbrain level at stage 16, expression of let-7a in the dorsal half of the neural tube (arrow). B: Dorsal view, stage-25 embryo shows hindbrain let-7k label similar to A. C–F: Complex neural expression pattern of miR-9 in forebrain or telencephalic vesicles (C, arrow) and diencephalon (arrowhead) at stage 22. D: Dorsal view, stage 24, expression in the hindbrain varies between rhombomeres, is absent in the floor plate and stronger at the margin of the roof plate. E: A transverse section of the spinal cord of the embryo in D; expression is strongest in the dorsal margin adjacent to the roof plate (near top) and in the proliferating mantle layer (arrowheads). F: View looking down into the opened midbrain at stage 24, showing wing-like projections coming from the diencephalon (arrows), coincident with the forming optic tectum. G: Dorsal view, stage 23, miR-10b expression in the spinal cord. H: Dorsal view, stage 10, mir-17-5p expression in the head surface ectoderm and caudal neural plate. I: Dorsal view, stage 24 (same embryo as in Fig. 5D) shows expression of miR-20a in the dorsal margins of the hindbrain. J: Transverse section of I. K: Lateral view, stage 20, expression of miR-20b in all tissues, with higher levels in the wing and midbrain. L: Transverse section of embryo in K showing label in the mesencephalon. M: Dorsal view, stage 20, expression of miR-106 in the neural tube. N: Dorsal view, stage 21, shows similar expression of Mir-124a including hindbrain and midbrain (excluding floor plate, arrowhead, and roof plate, arrow. O: Dorsal view at stage 21 shows miR-124b expression in spinal cord. P: Transverse section of O, mantle zone, and exclusion from floor and roof plate. Q: Transverse section of stage-23 embryo also labeled with miR-124b showing label in the pituitary rudiment at the base of the diencephalon. R: Dorsal view, stage-25 expression of miR-135 in hind and midbrain, in the floor plate (arrowhead) and roof plate (arrow), respectively; a pattern apparently complementary to 124a (see N). S: Lateral view shows CNS expression of miR-153 at stage 21. T,U: Lateral views of miR-183 label in cranial ganglia (T, arrowheads; stage 19) and spinal ganglia (U, stage 23). V: Lateral view, mir-184 at stage 17 in the cranial ganglia (arrowheads). W: Transverse section of another embryo showing the same probe hybridizing in lens at stage 16. X: Right frontal view at stage 25; neural expression of miR-187 is limited to the dorsal closure line of the CNS. Y,Z: Lateral view, stage 20 showing miR-204 in the outer layer of the retina (neural retina) in whole mount and (Y) transverse section (arrow; Z). A': Whole mount and transverse section showing miR-200b expression in the otic placodes (arrow). B':Transverse section shows expression of miR-218 in the motor horns (mh) of the spinal cord at stage 25 (also in the roof of the hindbrain, not shown). C': Dorsal view at stage 12; D': lateral view at stage 21, expression of miR-219 in the neural tube/spinal cord. E': Transverse section of the embryo in D', expression in the roof plate and dorsal-most spinal cord, in the margin between the ventricular and mantle zone, with heightened expression at the sulcus limitans (arrowhead). F': Dorsal view in the roof of the hindbrain labeled with miR-449 at stage 20.
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