<i>integrinα5</i> Expression in Pharyngeal Endoderm and Cranial Neural Crest

<div><p>(A) At the 32-cell stage, strong maternal <i>integrinα5</i> expression is seen.</p> <p>(B) At 60% epiboly, <i>integrinα5</i> expresses broadly throughout the mesendoderm.</p> <p>(C) Dorsal view of a 1-s-stage embryo. <i>integrinα5</i> transcript is concentrated in the ectoderm at the edge of the neural plate (black arrow), in scattered presumptive endodermal cells, and in the first somite (white arrow).</p> <p>(D and E) Dorsal (D) and lateral (E) views of a 5-s-stage embryo show ectodermal (arrows) and pharyngeal endodermal (arrowhead) expression domains of <i>integrinα5</i>. Ectodermal <i>integrinα5</i> expression includes migratory hyoid crest, otic placode, and forebrain.</p> <p>(F) At the 12-s stage, <i>integrinα5</i> continues to be expressed in the pharyngeal endoderm (black arrowhead), postmigratory hyoid crest (arrow), ear (red arrowhead), and forebrain.</p> <p>(G–J) At 18 hpf, a dorsal view of an embryo stained for <i>integrinα5</i> transcript (G) shows approximate axial levels at which cross-sections were prepared. (H) A cross-section at the level of the first pouch shows strong <i>integrinα5</i> expression in the pharyngeal endoderm (arrowhead). (I) A cross-section at the level of the hyoid arch shows expression of <i>integrinα5</i> in neural crest (arrow) and pharyngeal endoderm (arrowhead). (J) A cross-section at the level of the ear shows <i>integrinα5</i> expression in the otic epithelium (red arrowhead) and pharyngeal endoderm (black arrowhead).</p> <p>(K and L) At 26-hpf (K) and 38-hpf (L) stages, <i>integrinα5</i> transcript is enriched in the region of the most recent forming pharyngeal pouch (arrowheads) and in patches of crest (arrows).</p> <p>Scale bars: (A–C), (F), and (G): 100 μm; (D), (E), and (H–L): 50 μm.</p></div>