Although there is the possibility of recovering the embryos originated in the maternal womb with uterine washes, it is advisable to obtain them with in vitro fertilization procedures.
Furthermore, to minimize the risk of contamination with parental and / or extraneous cells, the ICSI procedure is recommendable, where the operator injects only one sperm in each of the ova, devoid of granulosa cells and washed.
The woman must receive hormonal medication so that several follicles can mature. Later the mature follicles are punctured to recover the oocytes of its interior
The oocytes and semen are processed before performing the ICSI procedure. The fertilized oocytes are normally kept in culture for three days.
To obtain the blastomere from the clived embryo or several cells of the trophectoderm of the blastocyst is necessary to make a drilling in the pellucid zone (ZP).
The drilling of pellucid zone can be done in several ways:
1) Mechanics: trying to cut a portion of the ZP with a micropipette
2) Chemistry: trying to dissolve a portion of the ZP with an acid-Tyrode solution
3) With Laser: doing some laser shots modulated through the optical system of the microscope. We prefer the latter method because in a single step it allows aspiration of the blastomere and above all because it is considered more innocuous for the survival of the embryo.
Prior to the biopsy, the embryos are placed in a suitable medium to loosen the cell junctions. Subsequently they are placed each one of them in microdrops under oil perfectly labeled. With the help of the micromanipulative microscope, the embryo that is going to be biopsied is placed in the center of the field and it is focused with the objective of 400 increases which allows the passage of the laser beams. The blastomere that is to be aspirated is selected by positioning it at time 3 and it is fastened to the embryo at hour 9 with a holding pipette.
The cell that is chosen must have a single nucleus. According to the size of the cell, one or two 15-millisecond laser shots are practiced in the ZP adjacent to the blastomere to be extracted. Once the area has been drilled the pipette is inserted and the blastomere is gently aspirated until it is removed. When a trophoectoderm biopsy is performed, it is preferable to perforate the ZP on day 4 and obtain part of the trophoectoderm that is hatching.
When the disorder is chromosomal the genetic study can be realized with fluorescent in situ hybridization technique (FISH), comparative genomic hibridization (CGH) or quantitative fluorescent PCR (QF-PCR). On the other hand, if the disorder is genic, it will be analyzed by minisequencing or by linkage analysis.