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Plate 1

Fig. 1.

  • Left lateral view of model of embryonic body viewed in the plane of section.
  • X 100. Yolk-sac, amnion, and body-stalk have been cut away.

Fig. 2.

  • Dorsal view of the same model.

Both views show open neural groove. Otic plates and V ganglia appear as darker, rounded areas, the former larger and farther lateral, in the region of the rhombencephalon.

Outlines of the underlying somites and in figure 2 the left umbilical vein.

At the posterior end of the body the broad, dark line indicates the primitive-streak region with the primitive node at its anterior end and the cloacal membrane at the posterior end.

Projecting from the cut surface of the body-stalk are the two umbilical arteries, with their branches to form the ventral venous plexus (cf . figs. 3 and 4) ; between the arteries is the allantois.

In figure 1, first ectodermic pocket in front of left otic plate, opposite midbrain flexure.

Embryo at Segmentation: Figure A | Plate 1 | Plate 2 | Plate 3 | Plate 4 | Plate 5 | Carnegie stage 9 | Carnegie Embryo 1878


Ingalls NW. A human embryo at the beginning of segmentation, with special reference to the vascular system. (1920) Contrib. Embryol., Carnegie Inst. Wash. Publ. 274, 11: 61-90.

Cite this page: Hill, M.A. (2024, June 21) Embryology Ingalls1920plate01.jpg. Retrieved from

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