What Does it Mean to Culture an Embryo?

Embryo culture is a major step in the process of in vitro fertilization (IVF). Its purpose is to support and promote the growth of fertilized eggs into multicelled embryos. While the particular steps of embryo culture vary slightly among facilities, it is possible to provide a general outline of the procedure and its place in the IVF process.

The Initial Steps of IVF

• If you undergo in vitro fertilization, the process typically begins with the use of fertility drugs to boost egg production. Normally, the body produces one egg a month, but fertility medications induce the production of several eggs at a time. If you are unable to produce eggs, this step will be omitted and donor eggs may be used for the rest of the process. If your own eggs are used, they will be removed through a minor surgical procedure.

Beginning Embryo Culture

• The process of embryo culture begins once viable eggs are available. Upon removal, your doctor will protect your eggs from harmful pH changes with a special buffer solution. After this solution is applied your eggs will be transferred to a fertilization medium that contains a mixture of sugars, salts, protein, amino acids and additional nutrients. The eggs are then combined with precisely measured amounts of sperm and left for a few hours while the fertilization process occurs. Typically, your doctor will allow fertilization to happen naturally, but in some cases he may decide to directly introduce sperm into the eggs. After fertilization occurs, the eggs are transferred to what is known as a cleavage (splitting) medium. This material is specifically designed to promote the development of the fertilized eggs into multicelled embryos.

Options and Outcomes

• The developing embryos are left in the cleavage medium for about 3 days. After this point, the next step in embryo culture depends on particulars decided by you and your doctor. If you are concerned about the possibility of passing on a hereditary disease to your children, your doctor may perform a procedure called pre-implantation genetic diagnosis (PGD). In PGD, single cells taken from each embryo are tested for genetic disorders. If any disorders are present, you may discontinue the IVF process at this point.

  If you proceed with IVF, and have decided on implantation of your embryo (or embryos) after 3 days of development, the selected number of embryos will be removed with a small amount of the cleavage medium and transferred to your uterus.

  If you have decided to let your embryos develop further before implantation, they will be placed in a different type of medium---called a blastocyst medium---which will support them during their next stage of development. You may also implant some embryos and allow the rest to develop further.

  After another 2 to 3 days, you will need to either implant the remaining embryos or safeguard them for future use in a low-temperature state called cryopreservation. If you choose implantation, your embryos will be removed with a small amount of blastocyst medium and transferred to your uterus.