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Fig. 3. The spatial pattern of expression of Smad8 in
developing Xenopus embryos is similar to that of
BMP-4, as analyzed by whole-mount in situ
hybridization. (A,B) Vegetal views of gastrulae
hybridized with a Smad8 antisense riboprobe. Smad8
transcripts are uniformly distributed at the onset of
gastrulation (stage 10) (A) but become restricted to
cells on the ventral (V) side by the stage 11 (B).
Arrows indicate the border of expression between
ventral and dorsal (D) cells. (C) Lateral view of a
neurula (stage 15) stage embryo (anterior to the left).
Smad8 transcripts are ventrally restricted and
concentrated in cells near the anterior end.
(D-F) Lateral views of stage 22 (D), stage 25 (E) and
stage 27 (F) embryos (anterior to the left, ventral
down). During these stages, expression of Smad8
becomes increasingly restricted to the heart anlage
(closed arrowhead), to dorsal regions of the eye
(arrow), and to the brain (open arrowhead). (F) In
tailbud stage embryos, weak expression of Smad8 is
observed in the otic vesicle (white arrow), and discrete
bands of Smad8-expressing cells are observed in the anterior central nervous system (inset). (G) Lateral views of stage 30/31 embryos
hybridized with Smad8 (top) and BMP-4 (bottom) probes. Both genes are expressed in the eye, the otic vesicle (white arrow), the brain and the
heart anlage, while Smad8 (asterisk), but not BMP-4, is expressed in the olfactory placode. (H) Transverse section of a stage 27 embryo at the
level of the hindbrain. Expression of Smad8 is restricted to the dorsal part of the brain (open arrowhead). (I) Transverse sections of stage 34/35
embryos at the level of the forebrain. (Left) Expression of Smad8 in the dorsal forebrain (open arrowhead), eye (arrow) and heart (closed
arrowhead) is observed. (Right) Higher magnification view demonstrates expression throughout the heart. Embryos shown in (C-E,G) were
cleared in benzyl benzoate:benzyl alcohol (2:1). |
