Blastocyst culture

Prolonging the cultivation of an embryo is a method whereby we are able to acquire additional information concerning the vitality of embryos in fertility treatments. Prolonged cultivation can be used in both IVF and ICSI treatments. It does not alter hormone stimulation.

During treatment, the embryos are usually cultivated 2–3 days after fertilization. The embryos have divided into 2–8 cells by the time they are implanted into the uterus. At this point, choosing the most robust embryos to be implanted may be difficult because there may be many good quality embryos. By cultivating the embryos a bit longer, we are able to select the most robust embryos that continue dividing and developing.

The embryos are cultivated 4–5 days before being implanted into the uterus. At this stage, the embryo has more than 100 cells and it is in either the morula or blastula phase. This corresponds to the stage of development in a natural pregnancy as it makes its way to the uterus. At the morula stage, the embryo is a cluster of cells that can no longer be precisely counted. At the blastula stage, the cells' first phase of differentiation has occurred. The tissues of the fetus develop from formed tissue mass in the inner cell and the tissue of its placenta develops from the cell tissue surrounding it. At the blastula stage of development, the embryo is ready to attach itself to the wall of the uterus after first having hatched from the zona. The probability that an embryo, which has reached this stage, will attach to the uterus is significant. For this reason, implanting just one embryo is easier, reducing the risk of a multi-fetal pregnancy.

Prolonging the cultivation of an embryo is a feasible alternative in cases where the embryo has not attached to the uterus in previous treatments. One disadvantage to prolonged cultivation is that only about 40–60% of the embryos develop into blastula and it is possible that all embryos cease to develop in which case an embryo implant is no longer possible.

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A blog by Tone Bråten

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