Skip Navigation
The Endowment for Human Development
The Endowment for Human Development
Improving lifelong health one pregnancy at a time.
Donate Now Get Free Videos

Image Gallery

Two-Cell Human Embryo

36 hours

From The Biology of Prenatal Development.Buy Now

Note:

Each cell in the early embryo is called a blastomere.

Label Key:

1. perivitelline space
2. outline of blastomere #1
3. zona pellucida
4. cell membrane of blastomere #2
All ages referenced to fertilization, not last menstrual period.
Human Zygote
Human Zygote
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
Free resources and training for educators
Tell your story. Create your own pregnancy calendar.