When does the implantation take place? | The implantation of the egg cell

When does the implantation take place?

The current procedure for the implantation of an egg cell is as follows:

• During the 2nd to 5th day of embryonic development, the germ migrates through the fallopian tube towards the uterus.
• On day 5, the blastocyst hatches out of the vitreous and is ready for implantation.
• The implantation takes place on the following 6th day of embryonic development. In some sources, the 5th day is also indicated as the implantation day, as this is when the attachment of the blastocyst to the endometrium begins.
• About a week later, at the beginning of the second week, the implantation is complete.

The egg reaches the uterus approximately on the 5th day after fertilization. On this day, the blastocyst hatches out of the protective glass skin (zona pellucida) and can attach to the lining of the uterus. The first contact between the blastocyst and the uterine lining takes place on the 5th or 6th day after fertilization. It takes about 7-8 days for the implantation to be completely complete, so that by the beginning of the second week after fertilization, the implantation of the egg is complete.

What is the implantation syringe?

The implantation syringe is used for in vitro fertilization (IVF). The drug triptorelin (trade name: Decapeptyl) is injected as a depot. The drug acts analogously to the body’s own hormone GnRH (gonadotropin-releasing hormone).

GnRH is naturally released in bursts by the body and has a stimulating effect on the hormones FSH (follicle-stimulating hormone) and LH (lutenising hormone). These in turn are important for the release of the hormones estrogen and progesterone. If the implantation injection is given regularly over the course of a cycle, it cancels out the intermittent release of GnRH and thus inhibits the secretion of FSH, LH, estrogen and progesterone.

In IVF, this effect is desired, since the first step is to over-stimulate the ovaries as much as possible so that the individual oocytes become as large as possible. For example, if LH were not inhibited by the implantation injection, ovulation would occur before the eggs were large enough for retrieval and in vitro fertilisation. Another use of triptorelin is in short-term administration about 6 days after ovarian puncture.

The short-term administration of Triptorelin increases the production of hormones as opposed to continuous administration. The increased production is intended to promote implantation. That this can be an advantage for implantation has also been proven in scientific studies. Nevertheless, the use of the implantation syringe is still controversial and is handled differently by fertility centers.