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

48 hours

Source: Centro Riproduzione Assistita, Catania, Italy.

Label Key:

1. blastomere #1
2. blastomere #2
3. blastomere #3
4. blastomere #4
5. zona pellucida
6. inside border of zona pellucida
7. perivitelline space
All ages referenced to fertilization, not last menstrual period.
Three-Cell Embryo
Three-Cell Embryo
Four-Cell Human Embryo
Four-Cell Human Embryo
Four-Cell Embryo
Four-Cell Embryo
Five-Cell Embryo
Five-Cell Embryo
Six-Cell Embryo
Six-Cell Embryo
Seven-Cell Embryo
Seven-Cell Embryo
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