Although the most common procedure in PGD is to carry out a genetic analysis of the embryos, there is also the possibility of analysing the genetic content of the eggs obtained for IVF by means of a biopsy of the polar corpuscle.
The polar corpuscles are cells with no function that are formed during meiosis and disappear instantly after fertilization. Therefore, the polar corpuscle biopsy is performed before fertilization takes place. In this way, the eggs with the best possibilities of achieving a good development of the pregnancy are selected.
The analysis of one of these cells will not affect the future development of the embryo. However, it will not be possible to detect anomalies that occur after fertilization nor will it provide genetic information of paternal origin, only of maternal origin.