6.1. In Vitro Maturation
6.2. Spindle - View
6.3. Pre-Implantation - Diagnostics
6.4. Polar Body Analysis
6.5. Blastomere Biopsy (performed on day 3 embryos)
6.6. Trophectoderm - Biopsy on blastocysts
6.7. Assisted Hatching - (helping the embryos to "hatch")
6.1. In Vitro Maturation
In some special cases or if conventional stimulation for IVF
is contra-indicated in a woman, In Vitro Maturation (IVM) may present another therapeutic option. The method involves collecting oocytes from immature follicles that are subsequently left to mature in a culture medium.
So far, success has been limited and scientific research has not yet been concluded. At our centers we perform this technique at the most advanced state of the art international standards. After appropriate consultation, we offer In Vitro Maturation to the following patients:
- Patients prior to chemotherapy when it is too late for ovarian stimulation and this procedure would only lead to further complications.
The disadvantages of an IVM are as follows:
- Overall, only few egg cells mature in the petri dish. Furthermore, there might be negative effects on the growth processes of embryos and fetuses having developed from such eggs.
- The examination of human embryos revealed that 80% of all embryos resulting from IVM presented chromosomal disorders.
6.2. Spindle View
The spindle is an essential organelle of the egg and plays a central role in meiotic development of human eggs . The spindle is responsible for accurate alignment and distribution of the chromosomes during cell division.
In 15-20% of all cases the mature egg lacks the spindle before being fertilized by a sperm. The presence of the spindle is – in addition to the first polar body – an indicator for maturation of the egg cell.
Increasing female age is associated with more spindle disorders. The absence of the spindle correlates with considerably reduced fertilization rates and poor or even no embryonic development.
The position of the spindle during ICSI / IMSI affects further embryonic development, too. Usually, the egg is positioned in such a way that the first polar body is at 12 o`clock and the injection of the sperm cell is performed at the 3 o` clock position. If the spindle isn’t optimally aligned (the spindle is normally close to the first polar body and thus quite in a distance from the site where the sperm is injected into the cytoplasm) it might be accidentally damaged when using a glass pipette for sperm injection, thus leading to the destruction of the egg .
Even in cases of repeatedly failed fertilization, spindle view represents an option (where appropriate, subject to be discussed with a doctor).
Picture: Display of spindle with the chromosomes within a mature egg and in the polar body, respectively
6.3. Pre - Implantation - Diagnostics
Pre-Implantation-Diagnostics (PID) or Pre-Implantation-Genetic-Diagnosis (PGD) as it is known in Anglo-American countries has originally been developed as an alternative to prenatal diagnosis. Prenatal diagnosis is only possible when a pregnancy is already established, whereas PID can be performed on the embryo prior to the achievement of a pregnancy.
The PGD is performed by examining a single cell with regard to aneuploidy
(mal-distribution of chromosomes
) and genetic diseases (overview, genetic diseases
in detail, example: retinoblastoma
). This can either be done by using the Polymerase Chain Reaction
(PCR) or the Fluorescence In Situ Hybridization
The PID/PGD also permits HLA-genotyping in embryos. HLA-genotyping is a valuable approach if there is a medical indication, e.g. a child suffering from a severe disease and whose life may be saved through the use of stem cells harvested from the umbilical cord blood
of an HLA-identical sibling (such as e.g. Fanconi-Anemia, Leukemia, Auto-Immune diseases…).
If, due to a malignant disease, a child’s bone marrow has to be destroyed by chemotherapy or radiotherapy, the sick child’s only chance of survival is either a matching bone marrow donation from a sibling or another suitable donor or the transplantation of stem cells from a cord blood donor to rebuild the hematopoietic system.
6.4. Polar Body Analysis
Polar body testing allows conclusions to be drawn regarding the mother's genetic contribution (oocyte) to the embryo. In this way it is possible to confirm or rule out the mal-distribution of chromosomes
and the genetic predisposition towards certain diseases with a high degree of probability.
This technique can be used to reduce the risk of miscarriage especially in patients of advanced maternal age and it may lead to slightly increased pregnancy rates. We are pleased to provide you with further details on this technique during a personal consultation.
6.5. Blastomere - Biopsy (performed on day 3 embryos)
The biopsy is performed by removing a single cell or a maximum of two cells (blastomere
) from the embryo - usually on the 3rd day after fertilization at the 6 - 8 cell stage.
This diagnostics is used mainly in cases of a specific genetic disorder
running in a family and is specifically designed to diagnose whether an embryo is also carrier of the genetic condition of concern. Only the embryos that are predicted to be free of the genetic condition are used for embryo-transfer.
In certain cases, this diagnostics can be suitable for investigating chromosomal disorders (aneuploidies) (e.g. reciprocal translocations
To date, Polar Body Testing still is the “Gold Standard” in aneuploidy-screening. We were able to show this together with the late Yury Verlinsky
who pioneered the PID.
We offer blastomere analysis for PGD/PID to be performed on blastomeres at our IVF-Center in Pilsen
in the Czech Republic.
6.6. Trophectoderm Biopsy on Blastocysts
The analysis of cells removed from the blastocyst on day 5 of embryonic development (trophectoderm biopsy
) is a technique that we are still in the process of further developing together with Alan Handyside
(pioneer in PGD
). This technique is not yet routinely on offer at our centers.
For the future we hope that, due to this technique, we will be in a position to detect chromosomal disorders (aneuploidy
) as well as genetic diseases (overview, genetic diseases
in detail) using a single diagnostic method (whereas to date, it is necessary to combine the methods of polar body diagnostics
and blastomere biopsy on day 3 embryos).
Analyzing blastocysts requires optimum freezing methods
, since this procedure mostly exceeds the maximum period for which embryos can be kept in culture. We are proud to count among our longtime staff members, Dr. Pierre Vanderzwalmen
, who is a pioneer in the field of cryopreservation.
6.7. Assisted Hatching - Helping the embryo to "hatch"
This method aims to make it easier for the developing embryo to hatch from the zona pellucida
. The assisted hatching procedure involves thinning or making a small hole in the zona pellucida. This can be performed mechanically, chemically or by using a laser-beam.
Performing this procedure is mainly useful in women with embryos having a very thick and tough zona pellucida (can easily be recognized using a polscope
or an ordinary light microscope). In particular with increasing age, the zona pellucida in some women becomes thicker and toughened. The same negative effects on the zona pellucida have been found in embryos after freezing and thawing.
Hatching embryo on day 5 Hatching embryo on day 6
Depending on the specific medical findings this technique is not routinely applied in our IVF laboratories, but according to individual requirements.
PICSI is a method to select mature sperm to be used for ICSI (ICSI
). The heads of mature spermatozoa have a specific receptor for hyaluronic acid (hyaluronan
). Hyaluronan is a major component of the protective layer that surrounds the oocytel. Immature sperm cells do not have such a receptor.
The hyaluronic acid binding test (PICSI) hyaluronan is used to select between immature and mature sperm cells. It has shown that mature sperm bind to hyaluronan where they can be isolated and used for ICSI
Washed sperm in a petri-dish Collecting the bound sperm
This technique is used in specific cases only. PICSI cannot replace the IMSI
technique, but is capable to complement it in certain cases.
The zona pellucida (Zona pellucida
,) is a glycoprotein membrane consisting of 3 layers surrounding an oocyte or embryo until the embryo performs zona-hatching on day 5 – 6 of embryogenesis at the blastocyst stage.
Using a polscope the zona pellucida can be assessed regarding the thickness of all three layers. Such data allow a better determination of quality properties of the zona pellucida of oocytes and embryos.
The inner layer of the zona pellucida in particular seems to be an important non-invasive marker for the development potential of an oocyte. There is evidence that in patients above 35 years of age the inner layer of the zona pellucida is thicker and the zona pellucida’s glycoproteins seem to be less structured.