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The Endowment for Human Development
The Endowment for Human Development
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Six-Cell Embryo

52 hours

Source: Centro Riproduzione Assistita, Catania, Italy.

Note:

The three-dimensional nature of the developing embryo becomes more evident with each cell division.

Label Key:

1. perivitelline space
2. zona pellucida
3. blastomere "in the middle"
All ages referenced to fertilization, not last menstrual period.
Four-Cell Embryo
Four-Cell Embryo
Five-Cell Embryo
Five-Cell Embryo
Six-Cell Embryo
Six-Cell Embryo
Seven-Cell Embryo
Seven-Cell Embryo
Eight-Cell Embryo
Eight-Cell Embryo
Nine-Cell Embryo
Nine-Cell Embryo
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