A general view of the specimen, showing the inner features of the embryo as well as its relation to the surrounding glands and of the implantation site. The upper surface of this reconstruction is the same as the section seen in figure 23. Approximately half the embryo, therefore, is included in this reconstruction. There is a large arteriovenous plexus in the surrounding endometrium, communicating with the trophoblast by means of direct capillaries. The intercommunicating nature of the trophoblast lacunae is evident. Particularly striking is the filmy, trabecular arrangement of the primitive extra-embryonic mesoblast, supporting the exocoelomic membrane and surrounding the embryo. The irregular plate of endoderm is evident, as is the thick germ disk and the thin, cleft-like amniotic cavity.
Fig. 36. Hertig and Rock, 1941.
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Keywords: amnion, amniotic cavity, arteriovenous plexus, embryo, endoderm, endometrium, exocoelom, extra-embryonic mesoblast, germ disk, implantation site, mouth of endometrial gland, primitive extra-embryonic mesoblast, sinusoid, trophoblast, trophoblast lacunae
Source: The Virtual Human Embryo.