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Fig. 8. Xtwi expression in Xenopus. Distribution of Xtwi mRNA shown by in situ hybridisation under dark field illumination, with corresponding bright field views below. Arrows indicate ectodermal Xtwi expression.
Scale bar = 400 km in C; 200 km in A,B,F; 160 pm in E; 130 pm in D.
A: Stage 12. Anterior transverse section. Xtwi transcripts present in lat-
eral region (arrows) of deep ectoderm (dp) and in dorsal mesoderm (m).
8: Stage 13. Anterior transverse section. Labelling in lateral region (ar-
rows) of deep ectoderm (dp) and in dorsal mesoderm (m) including no-
tochord (n). C: Stage 18. Anterior transverse section. Xtwi expression in
lateral aggregates of pre-migratory cephalic neural crest (arrows, c) and
in dorsal mesoderm (Ip, n) except myotomes (my). D: Stage 18. Trans-
verse trunk section. Xtwi transcripts in sub-notochordal endoderm (small
arrowheads, se), notochord (n) and dorso-lateral somite (large arrow-
heads), probably dermatome (dm). E: Stage 23. Transverse trunk sec-
tion. Xtwi transcripts in ventro-medial somite, probably sclerotome (s). F:
Stage 24. Horizontal head section. Xfm transcripts in cephalic neural
crest (c) migrating around prospective forebrain (nt) and, in aggregates,
into prospective branchial arch region (ba), with no expression in sur-
rounding visceral arch mesoderm (v). a = anterior; ar = archenteron; ba
= branchial arch region; c = cephalic neural crest; d = dorsal; dm =
dermatome; dp = deep ectoderm; e = endoderm; ep = epidermis; f =
neural fold; Ip = lateral plate mesoderm; m = mesoderm; my = myo-
tome; n = notochord; ng = neural groove; nt = neural tube; p = pos-
terior; s = sclerotome; se = sub-notochordal endoderm; sf = superficial
ectoderm; v = visceral arch mesoderm. |
