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The Endowment for Human Development
The Endowment for Human Development
Improving lifelong health one pregnancy at a time.
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Two-Cell Embryo

36 hours

Two-Cell Embryo [Click for next image]
Source: Centro Riproduzione Assistita, Catania, Italy.

Label Key:

1. zona pellucida
2. perivitelline space
3. blastomere #1
4. blastomere #2
5. cell membrane of blastomere #1
All ages referenced to fertilization, not last menstrual period.
The Zygote
The Zygote
Two-Cell Human Embryo
Two-Cell Human Embryo
Two-Cell Embryo
Two-Cell Embryo
Three-Cell Embryo
Three-Cell Embryo
Four-Cell Human Embryo
Four-Cell Human Embryo
Four-Cell Embryo
Four-Cell Embryo
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