A general view of the specimen, showing the inner features of the ovum as well as its relation to the surrounding glands and sinusoids of the implantation site. The upper surface of this reconstruction is the same as the section seen in figure 23. Approximately half the ovum, 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 trophoblastci lacunae is evident. Particularly striking is the filmy, trabecular arrangement of the primitive extraembryonic 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, cleftlike amniotic cavity.