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Fig. 3. Removal of lateral plate angioblasts eliminates dorsal aorta formation. (A) Schematic representation of microdissection experiment. Lateral plate mesoderm at the position of the posterior cardinal veins is removed, without damaging underlying endoderm or midline structures. Notochord (n), somite (s), endoderm (e) and mesoderm (m) are indicated. (B) Section through the unmanipulated region of the trunk of a stage 35 embryo, showing X-msr expression in the differentiated blood vessels. The posterior cardinal veins are evident laterally on each side of the embryo (arrows), and the single dorsal aorta (arrowhead) is located immediately under the hypochord. The position of the notochord is indicated (n). (C) Section through the dissected region of the trunk (more posterior) of the embryo shown in B. Posterior cardinal veins and dorsal aorta are not detectable by X-msr staining. Note the absence of damage to the midline structures as the hypochord, notochord and underlying endoderm are undisturbed. (D) Section through embryo where the lateral plate mesoderm on one side only was dissected. Note the absence of the posterior cardinal vein on the manipulated side of the embryo and the abnormality in the dorsal aorta at the midline (narrow arrowhead). The posterior cardinal vein on the opposite side is undisturbed (arrow). Bars, 25 μm (B-D). |
