Embryo Culture

Definition - What does Embryo Culture mean?

Embryo culture is an important step in the process of in vitro fertilization (IVF) where fertilized eggs develop into embryos in a lab setting under the supervision of an embryologist. The embryos grow for up to 6 days and are typically either frozen or transferred to a uterus. The goal of this step is to have high-quality embryos to transfer, which improves the chance of successful pregnancy.


FertilitySmarts explains Embryo Culture

The duration of embryo culture varies. Embryos could be transferred at the cleavage stage (day 2-4 after fertilization) or the blastocyst stage (day 5-6 after fertilization).

Embryo culture can be performed in two types of culture medium:

  1. Artificial culture media
  2. Autologous endometrial coculture—a medium created from top layer cells of the lining of the uterus. Coculture is used to provide embryos a natural environment to grow, with the intention of increasing the chance of pregnancy.


The key components of an artificial embryo culture media are carbohydrates, amino acids, buffers like 4-(2-hydroxyethyl)-1-piperazineethanesulphonic acid (HEPES at 21 mmol/L) and 3-(N-morpholino)-propanesulphonic acid (MOPS), macromolecules, growth factors, antibiotics, vitamins, and water.

Although the composition of the culture medium is important in the growth of pre-implantation embryos, other factors directly controlled by the laboratory are also significant in determining the efficiency of the culture medium and the growth of the embryo. The temperature, pH, and oxygen concentration of the culture system are critical.

The optimal temperature is unknown, but stable temperature maintenance around 37°C promotes embryo development and improves fertilization rates. The pH range for embryo culture media is between 7.2 and 7.4. Regarding oxygen, studies show that low oxygen concentration (5%) improves pregnancy rates.

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