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A1. The genetic material (DNA) of the sperm becomes active on the third day, between the 4 and 8-cell stage of development. Pror to the 8-cell stage, the developmental capacity of the embryo is derived from the inherent quality of the egg. After the 8-cell stage, the development of the embryo is governed by a combination of genetic instructions from both the sperm (paternal) and egg (maternal) DNA. Problems with embryo/fetal development that occur after the 8-cell stage of development can be attributed to either the sperm DNA, the egg DNA or both. However, problems in embryo development that arise prior to the 8-cell stage of development are a direct result of egg quality (the sperm DNA has not yet become active).
A2. Yes, the more fragmentation that is present, the less likely the embryo is to survive the thawing process.
A3. Yes, problems with the sperm DNA can cause miscarriage, but it is usually attributed to problems with the egg DNA. Aside from genetic problems, there are other causes of miscarriage. (e.g. immunological and thrombophilias). Yes, there is a correlation between poor sperm morphology and high DNA fragmentation indices. However, men with normal sperm morphology values can still have high DNA fragmentation indices, so just because the sperm morphology for the IVF cycle was better, it doesn't mean that the "chomatin problem" was gone.
Q4. The specific genes from the sperm DNA that are activated on Day 3 onward are not well understood at this point. This question will have to wait another 10-20 years for an answer.
Patricia,
Although it is technically possible to re-freeze embryos, it is not recommended. The reason your four remaining embryos were frozen together in one straw is because, relaistically, these embryos represent a single (reasonable) attempt at a successful pregnancy. It would be unlikely that the transfer of four frozen-thawed blastocysts would result in a multiple gestation (twins+).
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