Advances in assisted reproductive techniques

The intracytoplasmic sperm injection (ICSI) was the biggest advance after in vitro fertilization (IVF) and artificial insemination (AI), as far as assisted reproductive techniques are concerned. It’s a more complex technique since it places the sperm inside the egg with a microneedle.

In order to improve the ICSI, other techniques that allow the selection of the best spermatozoa have been developed, augmenting the possibilities of fertilisation and pregnancy rate.


The physiological ICSI, also known as PICSI, is a simple technique that allows to preselect the sperm that is going to be used in ICSI thanks to its attraction for the hyaluronan, a polysaccharide that can be found in the zona pellucida, which surrounds the egg and takes part in the recognition of the sperm, facilitating fertilisation.

The mature male gametes that don’t have fragmented DNA will be able to adhere to the synthetic zona pellucida. They will be stuck to the plate and will be selected, carefully retrieved and used for the injection in the egg’s cytoplasm (ICSI).


Until now the analysis and selection of the ejaculated or testicular spermatozoa for the ICSI technique was not that objective. It was based on the observation of the head, tail and mild connecting piece of the gametes, which were chosen by a specialist.

The IMSI, intracytoplasmic morphologically selected sperm injection, is a technique in which a powerful microscope that allows seeing the sperm 6,300 times bigger, is used. The observation of the morphology is very detailed, seeing it so big and without tinctures that may damage the sperm. This enables to discard all those gametes that present defects in their morphology and may cause problems during fertilisation.

This technique is also known as super ICSI.

Spermatozoa observed through IMSI


The technique annexin columns, also known as MACS (Magnetic Activated Cell Sorting) allows selecting the spermatozoa without fragmented DNA thanks to immunomagnetic selection. It allows separating healthy spermatozoa from dead spermatozoa or spermatozoa with fragmented DNA.

The spermatozoa with defects get stuck to the column, since annexin V attracts Phosphatidylserine, a phospholipid located in the membrane. If the spermatozoa present defects and the phosphatidylserine is accessible, it will adhere to the column. The healthy spermatozoa will go through the column and be used for ICSI.

Besides these techniques for selecting the spermatozoa there are also some others.

Embryoscope screen and incubator


It is a non invasive technique.It’s an incubator that allows observing the embryo at any moment, ever since the in vitro fertilisation took place until the transference to the uterus.

It takes pictures of the embryo automatically every 15 minutes and the greatest advantage is that it is not necessary to extract the embryo to observe its quality and development, which means the sample is not destabilised during the cultivation period.


Research is being carried out in how to improve the preimplantation diagnosis (PGD), since the problem lies in the fact that during some studies embryos are damaged. Furthermore, it allows the selection of healthy embryos but it doesn’t permit treating the illnesses of the embryo, which would be a great progress.

Woman looking at a pregnancy test

There’s also interest in improving the efficiency of the treatments: Not only increasing the pregnancy rate, but keeping it up with the transference of just one embryo. Multiple pregnancies are to be avoided, since they have economic and health consequences in the mother as well as in the children.

In order to reduce the number of transferred embryos, the embryos with the highest implantation potential must be identified. Embryoscope is a technique which aims to achieve this.

The factors that take place in multiple pregnancy in every patient must also be identified. In order to decide how many embryos are to be transferred, the age of the woman, the quantity of good quality embryos available at the moment of transference and the number of the previous IVF cycles must be taken into account.

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