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The Endowment for Human Development
The Endowment for Human Development
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Slideshow: Early Events

Nine-Cell Embryo

#48, Slide 11 of 24

57 hours

Source: Centro Riproduzione Assistita, Catania, Italy.

Note:

It is becoming more difficult to count the number of cells as more of them are out of focus when looking through the microscope.

Note:

The zona pellucida is appearing relatively thinner with time.

Label Key:

1. zona pellucida
2. perivitelline space
All ages referenced to fertilization, not last menstrual period.
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