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Grading Embryos

**Photo 2 Pro-nuclei:** This is a normally fertilized egg with 2 pronuclei. One nucleus contains half of the woman's DNA and the other nucleus contains half of man's DNA. **Photo 3 Pro-nuclei:** This is an abnormally fertilized egg with 3 pronuclei. One nucleus is from the woman's DNA, but the other two pronuclei are from two different 2 sperm (each sperm contributing 50% of their DNA) that penetrated this egg. The resulting embryo will typically die within 48 hours because it has 50% more DNA than normal. **Photo Grade 1:** This embryo has even, symmetrical cell sizes. There are no cellular fragments. This is a beautiful grade 1, 8-cell embryo. **Photo Grade 2:** The embryo is developing slowly. It has 5 cells, however it should have 8 cells at this stage. Each of the 4 cells visible in this view are different sizes. This is a grade 2 embryo. **Photo Grade 3:** Although this embryo has 8 cells, many cellular fragments are present. These are scattered throughout the embryo. Cell sizes are uneven. This embryo is a grade 3. One positive characteristic is the flattening of cells against each other. This shows that the embryo is alive and attempting to develop.