IN VITRO OOCYTE INSEMINATION (IVF OR ICSI)

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IN VITRO OOCYTE INSEMINATION (IVF OR ICSI)

The collected oocytes are prepared for insemination which can be performed by classical in vitro fertilization or ICSI technique. The most appropriate insemination technique will be selected on the day of procedure according to the quality of the gametes and the indication for treatment (e.g. indication for freezing of supernumerary oocytes and/or preimplantation genetic testing).

Classical In Vitro Fertilisation (IVF) consists of placing the selected sperm in contact with the retrieved oocytes still surrounded by the cells of the outer shell. The spermatozoa then have to cross the oocyte barriers on their own.

ICSI is a micromanipulation technique introduced in clinical practice to solve cases of infertility mainly related to a severe male factor (Palermo et al., 1992), but which is also indicated in case of previous failures with IVF technique and in case of limitations in the number of eggs available for insemination. There are no substantial differences in the preparation of an ICSI cycle compared to traditional IVF, with the exception of laboratory procedures.

 

This technique consists, in fact, in mechanically removing all the oocyte barriers, consisting of the cells of the cumulus and radiated corona, and introducing a single carefully selected spermatozoon directly into the oocyte cytoplasm.

ICSI offers the chance to observe and select gametes (oocytes and spermatozoa) before theyr used. After the removal of the cells from the cumulus, the oocyte is classified according to its nuclear maturity. The oocyte is considered mature and therefore usable for in vitro insemination if it has reached the metaphase II stage. At this stage, the oocyte contains the meiotic spindle (a birinfringent structure made up of microtubules that keep the oocyte chromosomes aligned on the metaphasic plane), which can be viewed through a poloscope (Rienzi et al., 2005).

Spermatozoa are normally observed and selected at 400 times magnification and are selected on the basis of their motility and morphological appearance.

In some cases in the presence of oocytes with particular morphological characteristics, Laser-ICSI can be performed (Rienzi et al., Fertil. Steril. 2001). This technique allows to thin a small part of the oocyte’s outer shell (zona pellucida) to reduce the pressure exerted during injection. This reduces the mechanical stress caused by the injection technique, which can damage the most fragile oocytes and compromise their survival.

Despite the proven efficiency of these techniques, in 10-20% of cases, fertilisation failure and/or embryo cell division may occur and therefore embryos cannot be transferred and/or cryopreserved.

IVF and ICSI steps

OVARIAN STIMULATION AND ULTRASOUND

AND/OR HORMONAL MONITORING

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OOCYTE

RETRIEVAL

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SPERM COLLECTION

AND PREPARATION

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IN VITRO OOCYTE

INSEMINATION (IVF OR ICSI)

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EMBRYO CULTURE UP

TO THE BLASTOCYST STAGE

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EMBRYO TRANSFER (ET)

AND CRYOPRESERVATION OF EMBRYOS

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