File:Hertig1945d fig02.jpg

Plate 1. Ova of the eighth day

Fig. 1. The middle cross section of an ovum not over 7.5 days of age. Above the somewhat eccentrically placed germ-disk is a barely discernible cleft—the amniotic cavity. Above the latter are a few dark, flattened amniogenic cells de-lamiznating in situ from the adjacent trophoblast. Toward the left of the chorionic cavity, a few primitive mesoblastic cells are seen which likewise arise from trophoblast by in situ delamination. Carnegie No. 8225, section 20-5-5, X 300 (minus).

Fig. 2. The middle cross section of a 7.5-day ovum. The cleft-like amniotic cavity lies above the germ-disk and beneath amniogenic cells arising from the adjacent trophoblast. A single, flattened meso-blastic cell is seen to the right of the germ-disk and lying upon the inner aspect of the tropho-blast. Carnegie No. 8020, section 6-5-9, X 300 (minus).

Fig. 3. The same ovum as fig. 2 but 7 sections removed. The amniotic cavity is less evident because of its smaller size although the amniogenic cells overlying it are more prominent. Carnegie No. 8020, section 6-5-2, X 300.

Fig. 4. The same ovum as shown in figs. 2 and 3 but the section passes to one side of the germ-disk. Note at the embryonic pole the three prominent mesoblastic cells which are delaminating in situ from the adjacent troplgoblast. A somewhat more advanced stage of this process is seen in the two mesoblastic cells shown in fig. 5. Carnegie 8020, section 6-3-6, X 300 (plus).

Fig. 5. A section of a. 7.5-day ovum (same specimen as figs. 2-4) showing a more advanced stage of mesoblastic formation. Note the two, nearly detached mesoblastic cells delaminating from, but still lightly attached to the trophoblast at the embryonic pole of the ovum. Carnegie 8020, section 6-4-3, X 300 (plus).

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  Fig 1 Carnegie No. 8225

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  Fig 2 Carnegie No. 8020

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  Fig 3 Carnegie No. 8020

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  Fig 4 Carnegie No. 8020

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  Fig 5 Carnegie No. 8020

Reference

Hertig AT. On the development of the amnion and exocoelomic membrane in the previllous human ovum. (1945) Yale J Biol Med. 18:107-15. PubMed 21007544

Cite this page: Hill, M.A. (2024, April 25) Embryology Hertig1945d fig02.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Hertig1945d_fig02.jpg

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