Oocyte maturation, egg immaturity, IVM, and the future of fertility!

Alisha Arora
8 min readJan 4, 2023

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How eggs mature — https://www.verywellfamily.com/oocyte-definition-and-development-1960091

In our middle school sex-ed class we all learned about the fact that once an egg is fertilized by a sperm a woman is pregnant and 9 months later a baby comes out!! But did you really get the full story? I know I had questions, I mean where do these eggs come from? What does fertilization even mean? and can all eggs be fertilized, shouldn’t that mean we can have hundreds of babies?

Well a few years later after I became fascinated by the concept of fertility and reproduction, I started to search for answers to some of my questions.

And so if you’re wondering, no you can’t have a hundred babies…

I mean it is theoretically possible for a woman to have hundreds of babies, as the female reproductive system is capable of producing a large number of oocytes, or eggs. However, the likelihood of a woman having hundreds of babies is extremely low and there are many resasons for that. First, not all oocytes are capable of successful fertilization. Factors such as age, hormonal imbalances, and environmental toxins can interfere with oocyte maturation and lead to egg immaturity, making fertilization less likely.

Age and just how physically demanding pregnancy is, is also why women don’t just have hundreds of kids.

But let’s dive deeper into the world of egg maturation and how over 50% of female infertility problems happen because of the egg and specifically egg maturity!

In this article I am going to dive into the science behind oocyte maturation, egg immaturity and the future of fertility!

The Basis of how eggs mature: Definition and Theories

Let’s first get familiar some terms and concepts :

  1. An egg — the female sex cell
  2. Meiosis — Cell division in sexually reproducing organisms
  3. Oocyte — used interchangeably with “egg” (a cell in an ovary which may undergo meiotic division to form an ovum)
  4. Ovulation — process of the release of an egg from one of a woman’s ovaries.

This is a female reproductive system, our eggs are stored in the ovary, the ovaries produce egg cells which mature into oocytes which are then transported to the fallopian tube where fertilization may occur. The process of oocyte maturation also occurs within the female reproductive system, specifically in the ovaries. The ovaries contain a large number of oocytes, or immature egg cells, that are present at birth.

Egg maturation consists of 3 stages and the process is called Oogenesis.

Oogenesis

Oogenesis is the process by which oocytes, or immature egg cells, are produced in the female reproductive system. It is an essential process in human reproduction, as a mature egg is necessary for fertilization to occur.

Oogenesis begins during fetal development, when a large number of oocytes are formed. These oocytes remain dormant until puberty, when a small number of them begin to mature each month as part of the menstrual cycle.

The process of oocyte maturation is regulated by hormones such as estrogen and progesterone. As an oocyte matures, it grows and develops within a structure called a follicle. When the oocyte is fully mature, it is released from the follicle during a process called ovulation.

If the mature oocyte is fertilized by a sperm cell, it will begin to divide and grow into an embryo. If fertilization does not occur, the oocyte and the lining of the uterus are shed during menstruation, and the cycle begins again.

The process of Oogenesis is completed in the 3 following stages:

  • Pre-natal
  • Antral
  • Pre-ovulatory

Preantral Stage:

This is the earliest stage of oogenesis, and it begins during fetal development. At this stage, a large number of oocytes are formed, each surrounded by a layer of cells called follicular cells. These oocytes remain dormant until puberty.

Antral Stage:

During the antral stage, which begins at puberty, a small number of oocytes begin to mature each month as part of the menstrual cycle. This process is regulated by hormones such as estrogen and progesterone. As the oocyte matures, it grows and develops within a structure called a follicle.

So for when you were as confused as me for getting your period just know this is when your oocytes that we’re formed when you were born actually became active and started to mature!

Pre-Ovulatory Stage:

When the oocyte is fully mature, it is released from the follicle during a process called ovulation. If the mature oocyte is fertilized by a sperm cell, it will begin to divide and grow into an embryo. If fertilization does not occur, the oocyte and the lining of the uterus are shed during menstruation, and the cycle begins again.

Egg immaturity is a condition in which an oocyte is unable to mature and develop properly. This can lead to problems with fertility, as a mature egg is necessary for fertilization to occur. Factors such as hormonal imbalances and environmental toxins can interfere with oocyte maturation and lead to egg immaturity.

Female Infertility: Egg immaturity

Egg immaturity is a condition in which an oocyte, or immature egg cell, is unable to mature and develop properly. This can lead to problems with fertility, as a mature egg is necessary for fertilization to occur.

The process of oocyte maturation is regulated by hormones such as estrogen and progesterone. During the menstrual cycle, a small number of oocytes begin to mature within the ovaries. As an oocyte matures, it grows and develops within a structure called a follicle. When the oocyte is fully mature, it is released from the follicle during ovulation. If the mature oocyte is fertilized by a sperm cell, it will begin to divide and grow into an embryo. If fertilization does not occur, the oocyte and the lining of the uterus are shed during menstruation, and the cycle begins again.

Problems with oocyte maturation can occur due to a variety of factors, including hormonal imbalances and environmental toxins. For example, high levels of stress or exposure to certain chemicals can interfere with hormone production and disrupt the normal process of oocyte maturation.

I like to think of egg immaturity as similar to a seed that is not yet ready to be planted. Just as a seed needs the right conditions and care to grow into a healthy plant, an oocyte, or immature egg cell, needs the right conditions and hormonal signals to mature and develop properly.

If a seed is not planted at the right time or in the right conditions, it may not grow and develop as it should. Similarly, if an oocyte is not exposed to the right hormonal signals at the right time, it may not mature and be capable of fertilization.

And now just as a gardener needs to be careful and attentive to the needs of their plants in order to help them grow and thrive, a woman’s reproductive system needs to be healthy and functioning properly in order to support the maturation and fertilization of her oocytes.

In-Vitro Maturation

So what’s the solution to this?

Well aside from the common hormonal medications/pills to try to mature the oocytes there’s something called In vitro maturation (IVM). IVM is a newer fertility procedure that involves harvesting immature eggs from the ovary and then maturing them in a laboratory setting. This is in contrast to traditional in vitro fertilization (IVF), which involves retrieving mature eggs from the ovary. This treatment is becoming increasingly popular as a way to help women with fertility issues due to problems with oocyte maturation.

During IVM, immature oocytes are removed from the ovaries and matured in a laboratory setting using hormone treatment. Once the oocytes are mature, they can be fertilized using standard in vitro fertilization (IVF) techniques. The resulting embryos can then be transferred back into the woman’s uterus, with the goal of achieving a successful pregnancy.

Live demonstration of IVM treatment

IVM has several potential advantages over traditional IVF techniques. For one, it is less invasive, as it does not require the use of fertility drugs to stimulate the ovaries. This can be beneficial for women who are unable to tolerate the side effects of these drugs or who have a high risk of developing complications such as ovarian hyperstimulation syndrome. IVM also is a more cost-effective option, as it requires fewer visits to the clinic and fewer medications.

One potential limitation of IVM is that it may not be as effective as traditional IVF in achieving pregnancy. There is some concern that the use of hormone treatment to mature the oocytes in the laboratory may affect their quality or viability.

Despite these limitations, IVM is a promising new treatment that is showing great potential for helping women with fertility issues due to problems with oocyte maturation. There have been several studies that have looked at the effectiveness of IVM. One review of 12 studies found that the pregnancy rate for IVM was similar to that of traditional in vitro fertilization (IVF), with an average success rate of around 20%. Another study found that the live birth rate for IVM was around 18%, which is lower than the live birth rate for IVF, but still higher than the live birth rate for certain other fertility treatments.

As research in this area continues to progress, it is likely that we will see an increasing number of fertility treatments utilizing IVM. This could revolutionize the way that fertility is approached, allowing more women to have successful pregnancies and start families.

Future of fertility and fertility research

As someone interested in the future of fertility and fertility research, I can’t help but feel excited about the potential advancements that are on the horizon. I think we’ll see a lot of progress in IVF and IVM treatments. Currently, the success rate for IVF is around 40% for women under 35, but I have a feeling that this rate will only continue to improve as researchers come up with new techniques and technologies to enhance the process.

Another aspect of fertility research that I find particularly interesting is the use of stem cells to repair or regenerate damaged reproductive organs. This has the potential to be a game-changer for people who are struggling with fertility issues due to injury or disease.

Of course, it’s not just about new treatments and therapies. I’m also hopeful that we’ll continue to learn more about the various factors that contribute to fertility and infertility. This understanding will be key in developing effective ways to help people conceive.

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