Fertilisation of the eggs through ICSI
ICSI is used for the fertilisation: the injection of one sperm into each egg. This fertilisation technique gives the most embryos and avoids problems in carrying out the genetic test on the embryonal cells: of all collected and fertilised eggs ninety per cent develop into an embryo.
The embryo biopsy
A biopsy involves removing a small amount of material from the embryos that have been produced in-vitro. There are two options here:
-
Option 1
On day three after fertilisation one (or two) cell(s) is/are removed to be analysed genetically.
While the diagnosis is made on the cell(s) that is/are removed, in the incubator the biopsied embryos continue to develop, up to day five.
-
Option 2
The introduction of new techniques now makes it possible to only carry out the genetic diagnosis on day five after fertilisation. In the resulting embryos a piece of trophectoderm is then removed. That delivers more cells and therefore more DNA material.
Because it takes more than twelve hours for that material to be analysed (and it is better not to return embryos later than day 5 or day 6), the biopsied embryos are frozen.
Continue reading under the figure.
Click on the figure for a larger view.
After analysis: possible status of each embryo
- ‘Healthy’ for the genetic defect tested for and of good morphological quality
- ‘Healthy’ for the genetic defect tested for and of poor morphological quality
- Embryo shows the defect tested for and morphologically is of good or poor quality
- In the case of HLA typing: HLA-compatible embryos versus ‘healthy’ but not HLA-compatible
- No diagnosis made