The term in vitro fertilisation (IVF) or test tube reproduction describes a medical reproduction method that involves fertilising an oocyte outside the body in the course of an infertility treatment. After hormonal stimulation oocytes are aspirated from the fallopian tubes. The operation and the hormonal treatment place a considerable strain on the woman whose oocytes are removed.

Sperm is collected through ejaculation and subsequently processed. The oocytes and spermatocytes are placed together in a test tube where fertilisation takes place. In vitro, the emerging zygote develops into an early embryo in the same way as it would in nature: Figure 1.

In the course of infertility treatment, up to three embryos are inserted into the woman’s uterus. All of them can develop into a child: Figure 2.

In the process of embryonic stem cell derivation, cells are extracted from the inner cell mass of the blastocyst and placed in a culture medium. This leads to the loss of the embryo’s integrity and ability to develop. Some of the extracted cells then develop into embryonic stem cells: Figure 3.