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Fig. 2. Comparison of the Sox10, Mitf and Bmp
expression patterns during the initial stages of chick eye development.
(A) Schematic illustrating the location of the section in H, showing
the nasal part of the optic vesicle at stage 10/11. (B) Bmp4
expression in the surface ectoderm overlying the optic vesicle following
whole-mount in situ hybridisation (13 somites). The optic primordium is shown
at stage 8 (6 somites; C,F,I,L,O), at stage 9 (7-9 somites; D,G,J,M,P) and
stage 10 (10-12 somites; E,H,K,N,Q). (C) At stage 8,
Sox10-positive neural crest cells are observed in the dorsal neural
folds of the prosencephalon (arrows). (D) Sox10-expressing
neural crest cells are detected in the dorsal-most region of the
prosencephalon (arrows) and no transcripts are detected distally. (E)
Sox10 expression is detected in neural crest cells overlying the
dorsal part of the optic vesicle (arrows). (F) At stage 8,
Mitf expression is not observed in the optic primordium (arrow).
(G) Mitf expression is strongest in the distal part of the
optic vesicle at stage 9 (arrows). The arrowheads indicate neural crest cells
dorsally. (H) At stage 10, Mitf expression is observed in the
presumptive RPE (dorsal optic vesicle) and in the distal part (arrows). See A
for the location of this section; see also R,S,T. (I) Bmp7
expression is observed in the ectoderm overlying the optic primordium at stage
8 (arrows), and diffuse expression is detected in the neural folds
(arrowheads). (J) Parallel section of the embryo shown in G. At stage
9, strong Bmp7 expression is observed in the overlying ectoderm
(arrows). Bmp7 transcripts are also detected in the dorsal ectoderm
that covers the neural crest cells (arrowheads). (K) Bmp7
expression in the ectoderm overlying the distal region of the optic vesicle at
stage 10 (arrows). Transcripts are still observed in the ectoderm overlying
the mesenchyme (arrowhead). (L) At stage 8, Bmp4 transcripts
are detected in the overlying ectoderm (arrow) and in the neural folds
(arrowheads). (M) Strong Bmp4 expression is detected in the
ectoderm overlying the distal portion of the optic vesicle at stage 9
(arrows). Weak or no expression is observed in the dorsal-most ectoderm
overlying the mesenchymal cells (arrowheads). (N) At stage 10,
Bmp4 expression is still strong in the ectoderm overlying the distal
portion of the optic vesicle (arrows), whereas weak expression is observed in
the ectoderm overlying the surrounding mesenchyme (arrowhead). Note that
Bmp4 expression appears to be stronger in the ectoderm overlying the
dorsal portion of the optic vesicle. (O) At stage 8, Bmp5
expression is strong in the dorsal midline, the neural folds (arrowheads).
Transcripts appear to be absent from the overlying ectoderm. (P)
Bmp5 expression weakens in the dorsal midline at stage 9 (arrowhead).
(Q) No Bmp5 transcripts are detected in the neuroepithelium of
the chick optic vesicle and surrounding tissues (arrow) at stage 10.
(R) Nasal region of the optic vesicle at stage 10. Mitf
expression in the distal and dorsal part of the optic vesicle (arrowheads).
(S) Higher magnification of the Mitf expression pattern in the
more-temporal region of the optic vesicle shown in H. Mitf expression
is detected in both the dorsal and distal region of the optic vesicle
(arrowheads), although expression weakens ventrally (arrow). (T) In the
most-temporal region of the optic vesicle, Mitf expression is
downregulated in the disto-ventral region (arrow).
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