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

Secondary Oocyte

Source: Centro Riproduzione Assistita, Catania, Italy.

Label Key:

1. zona pellucida
2. polar body
3. secondary oocyte
4. perivitelline space
All ages referenced to fertilization, not last menstrual period.
Chromosomes and the Nucleus
Chromosomes and the Nucleus
Sperm
Sperm
Secondary Oocyte
Secondary Oocyte
Single-Cell Embryo
Single-Cell Embryo
Zygote
Zygote
Human Zygote
Human Zygote
Free resources and training for educators
Tell your story. Create your own pregnancy calendar.