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Supplementary Figure 3. Expression of apelin during Xenopus embryogenesis.
The expression patterns of apelin during Xenopus embryogenesis were
determined by whole mount in situ hybridization. The embryos are shown as
frontal (A), dorsal (B), lateral (C-L) and ventral (M, N) views. Sections were cut
either transversally (O, O’, P, P’) or horizontally (Q, Q’). The planes of section are
shown in panels D and F. The embryonic stages are indicated. The embryos
shown in panels K and L were cleared to improve visualization of apelin staining.
Scale bars, 400 µm (A-J, M, N), 200 µm (K, L), and 100 µm (O-Q). (A, B) After
neural tube closure, apelin expression is detected in the head mesenchyme
(arrowheads) and the dorsal neural tube (arrow). (C ) At stage 24, apelin
expression is detected in the mesoderm component of the visceral arches
(arrowheads). (D) By stage 28, apelin expression is prominently detected in the
head mesenchyme (arrowhead), intermediate mesoderm (arrow), and the
visceral arches (asterisk). (E-G) Between stages 32 and 37/38, apelin expression
is primarily associated with intersomitic vein angiogenesis (arrowheads). Note
expression in the optic stalk region (arrow). (H-J) Apelin expression from stage
39 to 45 is no longer associated with intersomitic vein formation, but found in
specific areas of the head, trunk, abdomen, and tail, where blood vessels are
forming by angiogenesis. (K, L) Close-up view of the areas outlined in H and I,
respectively. Apelin expression is present in distinct patches of cells of the trunk
and tail, where new capillaries are forming. (M, N) Ventral views of the abdomen
of stage 42 and 45 tadpoles, where apelin expression is found in patches
(arrowhead) along the developing intestinal tract. (O , O ’ ) Transverse section
(with close-up view) through the head of a stage 28 embryo demonstrating
apelin expression in the head mesenchyme (arrow). (P, P’) Transverse section
(with close-up view) through the trunk of a stage 28 embryo, where apelin
expression is found in the intermediate mesoderm (arrow) adjacent to the
developing posterior cardinal vein (asterisk). (Q, Q’) Horizontal section (with
close-up view) through the visceral arches of a stage 35/36 embryo. Apelin
expression is found in distinct cell populations of the visceral arch mesenchyme. |
