Video Transcript
Where are embryos placed in the final stage of the IVF process? Uterus, vagina, cervix, ovary, or fallopian tube, also known as the oviduct.
IVF, or in vitro fertilization, is the process of fertilization that takes place outside of the body. Fertilization is the joining of the sperm and the egg, which can then form the embryo and can implant inside the uterus of the female to give rise to a pregnancy. Fertilization normally occurs in a part of the female reproductive system called the fallopian tube. But for those who are experiencing infertility, this process can be done outside the body in an IVF laboratory. In vitro is a term that scientists use to describe a process that takes place outside of a living organism.
In vitro is Latin for in glass, and in vitro fertilization refers to how fertilization can be performed outside the body in the glass of a test tube, although today it’s more common to use plastic vessels called Petri dishes. Now, let’s look a little closer at how this can be done.
There are six steps in the IVF process. The first step is ovarian stimulation. Here, the biological female whose eggs are to be extracted takes hormones in order to stimulate the production of multiple eggs. This happens in the ovaries which are attached to the end of the fallopian tubes. In this diagram here, the ovaries have been colored pink. These hormones cause eggs to develop inside follicles in the ovary, which you can see here colored as tiny black dots. These follicles grow in size over time. And once they’ve developed sufficiently, the next stage of the IVF process, the egg extraction, can begin.
A long needle is inserted into the ovary, and the fluid from each follicle, which contains an egg, is drained into test tubes. These eggs are suspended in the follicular fluid and can be extracted for IVF. The next step is to extract sperm from the semen. Semen is collected in a specimen cup following ejaculation and then processed in the lab in order to concentrate the sperm. Now that the eggs and sperm have been collected, fertilization can take place inside the lab.
Tiny drops of a special liquid called culture media are placed in a Petri dish to which sperm and eggs are added. If we look more closely at one of these drops, we can see a sperm fertilizing an egg. Once the egg is fertilized, the resulting embryo is cultured. This means that the embryos are placed in an incubator with ideal conditions for them to grow in the lab. Here, over the course of a few days, the embryo cells divide to eventually form a structure called the blastocyst.
The last step is the embryo transfer. The embryo is placed into the long tube of a catheter, which is then inserted into the vagina, then through the small opening of the cervix, and then into the uterus, where the embryo is deposited. After the embryo is transferred to the uterus, the embryo implants in the uterine lining or endometrium, where it can continue its development and give rise to a pregnancy. Therefore, embryos are placed in the uterus in the final stage of the IVF process.
