File:Ingalls1920plate03.jpg

Plate 3

Fig. 4. Vascular system as seen from the right side

• X 100. Color scheme as in figure 3.
• The ectoderm has been cut away close to the border of the medullary folds.
• The mesoderm of the embryo and adjacent yolksac has been removed to show the vessels embedded in it.
• In the vitelline plexus and that part of it which represents the yolk-sac portion of the vitelline (umbilical) artery, the endothelial vessels are represented in darker color than the less definitely lined channels.
• The same is true for the anterior portion of the dorsal aorta and the isolated vesicles in the roof of the fore-gut.
• Scattered blood-islands and other vascular formations are seen through the mesoderm of the yolk-sac.
• Anterior to the branch of the aorta (marked vitelline artery) is a second, more doubtful connection between the aorta and the vitelline plexus.

Embryo at Segmentation: Figure A | Plate 1 | Plate 2 | Plate 3 | Plate 4 | Plate 5 | Carnegie stage 9

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