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Single-Cell Embryo

1 hour

Source: Centro Riproduzione Assistita, Catania, Italy.

Note:

The two pronuclei—one male and one female—each contain the DNA from one parent that will join to form the unique genetic makeup of a new individual. The imminent mingling of the parents' DNA is the final step of fertilization.

Note:

The zona pellucida performs several vital roles in the reproductive process. Following the entrance of a single spermatozoon, it undergoes a reaction called the "zona reaction" rendering the wall of the oocyte/zygote impermeable to penetration by additional spermatozoa.

Label Key:

1. perivitelline space
2. zona pellucida
3. cell membrane
4. male and female pronuclei
5. polar body
All ages referenced to fertilization, not last menstrual period.
Sperm
Sperm
Secondary Oocyte
Secondary Oocyte
Single-Cell Embryo
Single-Cell Embryo
Zygote
Zygote
Human Zygote
Human Zygote
The Zygote
The Zygote


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