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FIG.2.Nonmuscle cardiac development in Xenopus. Images representthecardiac regions of embryos (stage 27 and stage 35) immunostained with anti-fibrillin (JB3). The secondary antibody was conjugated to Alexa 568. Ventral views of the heart regions of embryos are presented with the anterior of the embryo at the top. The stage 27 (A) and stage 35 (B) images were form ed by the digital merging of 28 and 36 optical sections 4 and 5 um apart, respectively (taken in gray scale), and digitally colored. At stage 27, the endocardial tube is not completely formed. The unlabeled arrowheads point to unpartitioned secreted material at the embryos midline. By stage 35 (B), a single heart tube has formed into a S shape; the sinus venosus is paired. Scale bar, 100um. |
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Display additional annotations [+]
| Gene |
Clone |
Species |
Stages |
Anatomy |
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tnnt2
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laevis
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NF stage 35 and 36
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heart
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myocardium
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muscle
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cardiac ventricle
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tnnt2
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laevis
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NF stage 41
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heart
,
myocardium
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muscle
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left atrium
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right atrium
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[+]
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tnnt2
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laevis
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NF stage 44
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heart
,
myocardium
,
muscle
,
left atrium
,
right atrium
,
[+]
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FIG. 4. Milestones of early cardiac development in Xenopus (continued). Embryos were double labeled with anti-cardiac troponin T (CT3) (red) and anti-fibrillin (JB3) (green) and optically sectioned. For each stage, the set of optical sections (35 to 53 sections 5 to 7 um thick) was digitally compiled in increments of 6 to 9 sections. Resulting ventral views of optical thick sections are presented. By stage 35 (A and B) the myocardial wall is closed and the heart tube has become twisted in a S shape; the chambers are now distinct. Stage 41 (C and D) The myocardium thickens and develops trabeculae; the atrium is posterior to the ventricle. At stage 44 (E and F) the single atrium begins to be partitioned by the forming septum and is pushed slightly anterior to the ventricle. Scale bar, 100um. |
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FIG. 5. Ventral-to-dorsal progression through a stage 46 Xenopus heart. Images were digitally created from a series of 48 optical sections (taken 5um apart) through a double-labeled stage 46 Xenopus heart (red, CT3; green, JB3). Image A represents the most ventral 8 images of this series, digitally merged; image B, the next 8, etc. The relative positioning of heart structures to one another, as well as an individual structure order of emergence within the series, can be established: the truncus arteriosus and ventricle are always most ventral (A). Progressing dorsally, the spiral valve (B) appears within the truncus. Next, the single atrioventricular valve (C) is seen overlying the atrial septum (D and E). Midway through the series (C and D), the first views of the atria, as well as the aortic branches, are viewed. Both atria and the sinus venosus are seen more dorsally (D and E). Finally, the back wall of the atria is seen, positioned most dorsal (F). Scale bar, 100 um. |
