Slideshow: Early Events

Morula: Twelve-Cell Embryo

#50, Slide 13 of 24

60 hours

Source: Centro Riproduzione Assistita, Catania, Italy.

Note:

This 12-cell embryo is now at the earliest stage at which the embryo can be called a "morula," which is the scientific word used to describe a ball of cells. This term will continue to apply until a cavity begins to form inside this spherically shaped clump of cells. The age is approximate.

Label Key:

1. zona pellucida

2. perivitelline space

All ages referenced to fertilization, not last menstrual period.

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