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Embryoblast
Pellucid zone
Trophoblast
Blastocyst cavity |
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Fig. 9
The blastocyst comes into being through compaction of the cells and the accumulation of intercellular fluid, leading to the formation of the blastocyst cavity. At this point, the embryoblast that lies inside (hump on the left side) consists of roughly 12 cells. At the same time, the enveloping trophoblast, made of a single cellular layer, contains around a hundred cells.
© Dr. A. Senn et al, CHUV Lausanne
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