Ovarian Follicle: Function and Growth

If you’re trying to conceive, odds are you’re going to be hearing about the “ovarian follicles” that mature in the ovaries over the menstrual cycle. But what exactly is an ovarian follicle, and why does it need to mature for ovulation? What if it grows too slow, and what can you do to help it along? Let’s run through what the ovarian follicles are for, and what you should know about follicle development.

What is the ovarian follicle?

ovarian follicle egg cell

“Ovarian follicles” are tiny sacs of fluid in the ovaries, which hold the eggs. Each follicle contains one egg cell (ovum). When the follicle matures, the egg will be released in a process called ovulation. This is what allows for an egg to be fertilized and lead to pregnancy.

You’re born with a finite supply of ovarian follicles – you’ll never grow more of them. You have about 2 million on the day you are born, but this number gradually declines as you age and the follicles die away naturally. By the time of your first period, there are about 200,000 remaining. After you start menstruating, you lose about 1000 each month. Each month, only 10 ovarian follicles begin to mature – and only one follicle actually makes it all the way to full maturity and ovulation.

After the egg escapes, the leftover follicle transforms into a structure called the corpus luteum, and releases progesterone to support a potential pregnancy. If you don’t happen to get pregnant in that cycle, then the corpus luteum breaks down, and you get your period.

How does the ovarian follicle mature?

ovarian follicle cycle

A resting ovarian follicle measures just 0.05 mm across, but as it ripens for possible ovulation, it grows to about 20 mm (0.8 in). If it’s the lucky “dominant follicle” (that is, the one that will release an egg at ovulation), then grows faster than the others, reaching a diameter of around 25 mm (just under 1 in).

That said, the time it takes for an ovarian follicle to grow depends on the individual, and varies with levels of hormones released during the menstrual cycle. If there’s not enough estrogen in your system, then it can take longer for the follicle to mature. As a result, your menstrual cycle could take longer than the average 28 days – lasting as long as 35 or 40 days in some cases. This kind of extended menstrual cycle can be a sign that your ovarian follicle is taking longer than usual to mature.

What slows ovarian follicle growth?

question wonder

The ovaries secrete the hormone estrogen in response to orders from the hypothalamus section of the brain. However, the hypothalamus is highly sensitive to physical and emotional stress, and cannot smoothly give orders to the ovaries during times of stress. This means less estrogen is secreted by the ovaries, and ovarian follicles take longer to reach maturity.

How to boost the growth of ovarian follicle


If ovarian follicle development is taking too long, it’s important to address the root cause of the problem. This could mean reducing the physical or emotional stress that you’re facing in daily life. Some good steps towards stress reduction and self-care can include devoting time to your hobbies, making sure that you get a good balance of physical exercise and sleep, and enjoying a healthy and nutritious diet.

On the other hand, poor estrogen production could be linked to an underlying physical condition. If you suspect this could be the case for you, speak to your doctor. Hormone replacement therapies are available to restore healthy estrogen levels and support ovarian follicle development.

Healthy ovarian follicle cycle starts with healthy lifestyle

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Learning more about the things your body is doing behind the scenes during the menstrual cycle can be empowering. You can’t necessarily control the rate at which your ovarian follicles develop, but there are many steps you can take to support general health, which can have a flow-on effect for your fertility cycle.

If you think your menstrual cycle is a bit out of whack, take a look at some of the lifestyle changes you can make to support your health, and speak to a gynecologist to see if there’s anything else going on with your follicle development.