Source: Centro Riproduzione Assistita, Catania, Italy. |
Note:The zona has served its purpose and is disintegrating just in time to free the embryo for the next step in the journey.Label Key:1. site of escape 2. portion of embryo outside the zona 3. portion of embryo still inside the zona 4. zona pellucida |
All ages referenced to fertilization, not last menstrual period. |