FIGURE SUMMARY
Title

An essential role for Fgfs in endodermal pouch formation influences later craniofacial skeletal patterning

Authors
Crump, J.G., Maves, L., Lawson, N.D., Weinstein, B.M., and Kimmel, C.B.
Source
Full text @ Development

Pharyngeal endoderm and cranial NCC defects in animals lacking Fgf8 and Fgf3. nkx2.7 (A-D) and axial (E-H) label pharyngeal endoderm during early pouch morphogenesis stages (18 hpf). nkx2.7 and axial are in blue, and, in E-H, krox-20 in red labels R3 and R5. In wildtype animals (A,E), the first pouch (p1: arrows) has formed anterior to R3, and a more posterior endodermal mass that will give rise to the remaining pouches (black lines) is situated adjacent to R4-R6 territory. The first pouch is variably lost in fgf8– animals (asterisk in B, question mark in F). Whereas pharyngeal endoderm develops normally in fgf3-MO animals (C,G), in fgf8–; fgf3-MO animals (D,H) pharyngeal endoderm is present as a single anterior mass (black line) and no pouches are evident. (I-P) dlx2, in blue, labels cranial NCC; in red (I-L), pax2a labels the MHB and krox-20 labels R3 and R5. (I) In 18 hpf wild-type animals, mandibular (1), hyoid (2), and branchial (3) NCC streams give rise to seven pharyngeal arches. (M) At 33 hpf, the third branchial stream has generated arches 3-5 and arches 6 and 7 have yet to separate. In fgf8– (J,N) and fgf3-MO (K,O) animals, the migration and coalescence of NCC to form the pharyngeal arches is largely normal. In fgf8–; fgf3-MO animals, the mandibular (1) stream is disorganized and hyoid and branchial streams are fused together (2/3) at 18 hpf (L). By 33 hpf (P), nearly all hyoid and branchial NCC are absent, and mandibular (1) NCC are present but reduced. Anterior is to the left in all panels. A-D are dorsal views, and E-P are lateral views. R3 and R5, rhombomeres 3 and 5; MHB, midbrain-hindbrain boundary; p1, first pouch. Scale bar: 50 µm.

Acknowledgments
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