Immature Egg

Definition - What does Immature Egg mean?

An immature egg is a follicle from the ovary that has not undergone the necessary cell division to reduce the number of chromosomes in the nucleus of the egg from 46 chromosomes to 23 chromosomes. Immature eggs are not prepared for fertilization by the sperm and will not produce a viable embryo. Fertility is affected when follicles do not mature.

FertilitySmarts explains Immature Egg

In order to produce and mature and viable egg during ovulation, ovarian follicles must undergo a cell division process called meiosis, which is a process of cell division specific to eggs and sperm. Meiosis reduces the number of chromosomes in the nucleus of the egg from 46 chromosomes to 23 chromosomes which allows for fertilization by the sperm. Smaller than average follicles found within the ovary may not mature readily and may be more likely to produce immature eggs. An immature egg in not capable of being fertilized by the sperm as the nucleus contains too many chromosomes.

During in vitro fertilization (IVF) the process of egg maturation may be stimulated with the hormone human chorionic gonadotropin (hCG) through what is called an hCG trigger shot. During the egg retrieval it is common for some immature eggs may be collected in addition to mature eggs. Simulation protocols can be adjusted to improve the rate of mature eggs retrieved if a high percentage of eggs are found to be immature.

It may be possible to take immature eggs collected during the egg retrieval process and mature them in the lab through in vitro maturation (IVM). These lab-matured eggs can then be fertilized by the sperm to produce an embryo.

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