XB-IMG-47809
Xenbase Image ID: 47809
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Figure 2. Expression of EphA4 and EphB1 in the branchial region. Whole-mount in situ hybridisation was carried out to detect EphA4 and EphB1 expression during branchial neural crest migration. (a–e) Expression pattern of EphA4. (a) A stage 19 embryo shown in dorsal–rostral view. Note the ventral domain of EphA4 expression in the presumptive branchial arch region coextensive with the EphA4-expressing neural crest. (b) A stage 23 embryo show in lateral view. EphA4-expressing neural crest has started to migrate, and the ventral domain has narrowed to a stripe at the rostral margin of the third arch. (c) A stage 26 embryo shown in lateral view. EphA4-expressing neural crest has migrated into the third branchial arch. (d) Coronal section through the ventral domain of EphA4 expression in the presumptive branchial arch region of a stage 19 embryo. Expression occurs in visceral mesoderm, and at lower levels in underlying endoderm. (e) Coronal section through ventral EphA4 expression domain in a stage 23 embryo. Expression is at low levels in visceral mesoderm, and at higher levels in a broader domain in the underlying endoderm. (f) Krox-20 gene expression in a stage 26 embryo. Expression in neural crest is restricted to the third branchial arch. (g–i) Expression pattern of EphB1. (g) At stage 25, EphB1 expression occurs in migrating third and fourth arch neural crest, and thus appears as a broader domain than EphA4. Expression also occurs in a ventral domain coextensive with the neural crest; the border of the neural crest is difficult to see because expression occurs at similar levels in the ventral region. (h) At stage 27, expression occurs in the fourth and more caudal branchial arches. (i) Section through stage 25 embryo. Expression is detected in neural crest, visceral mesoderm and endoderm. (j) Lateral view of EphA4 expression at stage 19 (see (a)), showing the ventral EphA4 expression domain in more detail. (k–m) Detection of EphA4 (strong staining in neural crest) plus EphB1 (weaker staining) expression during neural crest migration at stages 23 (k), 24 (l) and 26 (m). EphB1 expression extends caudal to EphA4 expression both in third arch neural crest and in the ventral domain. Abbreviations: r3/5, rhombomeres 3/5; n3/4, neural crest destined for third/fourth arch; v, ventral expression domain; fb, forebrain; cg, cement gland; pn, pronephros; ec, ectoderm; m, mesoderm; en, endoderm. Image published in: Smith A et al. (1997) Copyright © 1997. Image reproduced with permission of the Publisher, Elsevier B. V.
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