Neural crest streaming as an emergent property of tissue interactions during morphogenesis
Fig 1
The neural crest and its surroundings before and during migration.
(A) Cranial neural crest (NC) migrates in streams that are flanked by a variety of essential guidance cues corresponding with the epibranchial placodes. (B) Lateral view of Xenopus laevis embryo showing migrating NC by in situ hybridization (ISH) against Twist. (C-E) ISH showing expression of NC inhibitors Semaphorin 3F (C) and Versican (D), and the coinciding placodal cell pattern (E, Six1) during NC migration. (F-I) ISH showing pre-migratory NC, inhibitor expressions, and placode distribution before NC migration. Yellow outline on (G,H) indicate position of NC; (I) shows NC (Twist, blue) and placodes (Six1, purple) by double-ISH and embryo is shown in a slightly tilted dorso-lateral view. Twist adjacent to Six1 marks cranial NC. (J) Illustration of known NC-placode cell interactions and the hypothesis that this interaction leads to emergence of the NC stream pattern. Arrowheads on (B-E) indicate NC streams, ‘*’ marks the eye/ optic vesicle; scalebars: 300μm.