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Figure 1. Cardiac formation during Xenopus early embryogenesis. A: Precardiac mesoderm (PCM, blue) is formed on the prospective dorsal side of the early gastrula (stage 10). B-G: The region of PCM formation is defined by the expression of Nkx2.5 (arrowhead; Tonissen et al.,[1994]). B: By the end of the gastrula (stage 13), the PCM is fused and lies at the anterior end of the embryo. C: At the neurula (stage 18), the PCM is located on the ventral side behind the cement gland. D: At the early tail bud (stage 23), the PCM is separated. At the mid-tail bud (stage 28), the PCM is re-fused. F: At the late tail bud (stage 34), a tubular and beating heart is formed. G: At this point, the tadpole heart separates into the atrium and ventricle. A: Vegetal view, with dorsal upward. B-G: Ventral view, with anterior toward the left. |
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Display additional annotations [+]
Gene |
Clone |
Species |
Stages |
Anatomy |
vcan
|
|
laevis
|
NF stage 25
|
head region
,
mesoderm
,
presomitic mesoderm
,
cardiac mesoderm
,
cranial neural crest
,
[+]
|
has2
|
|
laevis
|
NF stage 25
|
head region
,
mesoderm
,
presomitic mesoderm
,
cardiac mesoderm
,
paraxial mesoderm
|
hapln3
|
|
laevis
|
NF stage 25
|
mesoderm
,
presomitic mesoderm
,
heart
,
cardiac mesoderm
,
otic region
,
[+]
|
|
|
Figure 3. Developmental expression profiles and knockdown analysis of XHAPLN3 and Xhas2. A-D: Whole-mount in situ hybridization of Nkx2.5 (A), XHAPLN3 (B), Xversican (C), and Xhas2 (D). Lateral views are shown, with the anterior toward the left and dorsal side upward. The arrowhead indicates the precardiac mesoderm (PCM). E-G: The effects of depleting XHAPLN3 and Xhas2 are validated by the pattern of XcTnI expression. Normal tadpole heart structure (E, arrow). F,G: However, both XHAPLN3-morphant (F) and Xhas2-morphant (G) show no XcTnI expression. Ventral views are shown, with anterior upward. |