File:Hertig1946b fig07.jpg

Fig. 7. A human embryo of approximately 20 - 21 days of age

A. A human embryo of approximately 20 - 21 days of age, measuring 1.6 mm in length. Fig. A. represents the chorion embedded within the endometrium and opened in such a way as to reveal the entire embryo when viewed from its left side. The yolk-sac is the most prominent feature of the embryo and is seen as a balloon-like mass whose distal surface is covered with blood islands. The embryonic disk itself together with its amnion is the thickened opaque mass where the embryo is attached to the chorion. See fig. B. for morphologic details of the embryo. Carnegie 7545, sequence 7, X5.

Fig. B. A cross section through the middle of a 20 - 21 day embryo. Note the enormous size of the yolk-sac containing blood islands Within its doublelayered wall. The embryo proper is the trilaminar mass between the yolk-sac and amniotic cavity and consists, from within outward, of primitive or gut entoderm, mesoderm and ectoderm. A portion of the chorion is seen below. Carnegie 7545, section 6-2-2, X60.

References

Hertig AT. lnvolution of tissues in fetal life: a review. (1946) Anat. Rec. 94: 96-116.

Cite this page: Hill, M.A. (2024, April 19) Embryology Hertig1946b fig07.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Hertig1946b_fig07.jpg

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