EMBRYO CULTURE UP TO THE BLASTOCYST STAGE

EMBRYO CULTURE UP TO THE BLASTOCYST STAGE

PGD, PGS, Diagnosi genetica preimpianto, Corte costituzionale

As a result of the fusion between the spermatozoon and the oocyte, a cascade of events is triggered which leads to the formation of the embryo. The signs of successful fertilization are conventionally assessed 16-18 hours after oocyte insemination (The Istanbul consensus workshop on embryo assessment , 2011). Inside the fertilized cell (zygote) is observed the presence of two pronuclei that carry respectively the genetic information of maternal and paternal origin. After an in vitro culture period extending up to the seventh day from the date of oocyte collection, the number of evolutionary embryos is evaluated.

The quality of the in vitro culture of oocytes/zygotes/embryos has a critical role: optimal pH and temperature conditions are guaranteed in our laboratory through the use of special culture media and an adequate number of incubators (>20) suitable to provide the best conditions for embryo development and growth.

To date, the strategy of choice for the identification of the embryo with greater developmental expertise remains the extension of culture to later stages of preimplantation development and, in particular, to the blastocyst stage (Glujovsky et al., 2016). The high selectivity of blastocyst culture allows a more accurate assessment of embryo viability and therefore allows for single embryo transfer policies, reducing the risk of onset of multiple pregnancy, but maintaining high rates of clinical pregnancy per cycle.

Blastocyst morphological classification systems take into account different parameters: the degree of blastocyst expansion and the morphological aspect of the trophectoderm cells and the internal cell mass, evaluated according to the number of cells and the degree of cell cohesion (Gardner and Schoolcraft, 1999). Compared to the morphological evaluation carried out at cleavage state, the evaluation of embryonic morphology seems to have a higher predictive value in terms of term pregnancy (Ahlstrom et al. 2014, Cimadomo et al., 2018).

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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