The dominant follicle in the right ovary is 11 mm. Dominant follicle in the left ovary: what does it look like and what causes the anomaly? Is it possible to increase the number of antral follicles

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The internal anatomy of the ovary, as well as the uterus, should be considered in relation to the various phases of the menstrual cycle.
The stroma of the ovary, which is the connective tissue basis of the cortical substance, is visualized sonographically as a zone of medium echogenicity, mainly located in the central parts of the ovary.
The cortical substance of the ovary contains follicles of varying degrees of maturity (follicular apparatus). Numerous (hundreds of thousands) primordial, primary, and secondary follicles are not detected by echography, since their size does not exceed 400 microns.

On days 5-7 of the cycle (early proliferation phase or early follicular phase), the visualized part of the follicular apparatus is represented mainly by 5-10 tertiary, or antral follicles. The latter have the appearance of rounded echo-negative inclusions with a diameter of 2-6 mm, located mainly along the periphery of the ovary. A network of spiral vessels around the developing follicle appears already at the beginning of the antral phase. At the same time, the blood flow is visualized in the form of a few color loci in the stroma and along the periphery of the antral follicles.

On days 8-10 of the cycle (medium proliferation or middle follicular phase), a dominant follicle usually appears, the diameter of which is already 12-15 mm and continues to increase, while the growth of other follicles stops, and they reach 8-10 mm in diameter, undergo atresia (which is echographically determined in a gradual decrease and disappearance by the end of the menstrual cycle). The blood supply of the dominant follicle usually comes from two or three stromal arteries, usually visualized along the periphery, or even in the wall of the latter. At the same time, Doppler parameters of stromal arteries and arteries of the dominant follicle do not differ significantly.

On days 11-14 of the cycle (late proliferation phase or late follicular phase), the dominant follicle increases by 2-3 mm per day, reaching 18-25 mm by the time of ovulation (average 20 mm). The prognostic signs of ovulation, indicating that the latter will occur in the next few hours, include: the diameter of the dominant follicle is 18 mm, a double contour around the latter, as well as fragmentary thickening and unevenness of the inner contour of the dominant follicle. Vascularization of the dominant follicle becomes subjectively more noticeable compared to other follicular structures, also only on the eve of ovulation.

Ovulation that has occurred can be echographically judged by the disappearance of the dominant follicle or a decrease in its size with deformation of the walls and the appearance of echogenic contents in the cavity, as well as the appearance of fluid in the Douglas space.

On days 15-18 of the cycle (early secretion phase or early luteal phase), a corpus luteum with a diameter of 15-20 mm (usually smaller than the dominant follicle) appears at the site of ovulation, having an irregular shape, uneven contours, and an extremely diverse internal echostructure of varying degrees of echogenicity. This peculiar echographic polymorphism can be easily explained by the morphological substrate of the corpus luteum nucleus, which is a blood clot in varying degrees of thrombosis and lysis.

On days 19-23 of the cycle (middle secretion phase or middle luteal phase), the “blooming” corpus luteum is characterized by a slight increase in diameter (up to 25-27 mm), as well as the appearance of an unevenly thickened echo-positive roller. The echogenicity of the contents due to lysis can gradually decrease until the formation of a "cystic" corpus luteum.
During the first days after ovulation, a dense, multi-layered vascular network is formed around the corpus luteum, which is especially pronounced in the flowering phase. On color Dopplerograms, a pronounced color ring appears around the corpus luteum, the blood flow in which is characterized by high speeds and low impedance. This is typical of violent physiological neovascularization.

On days 24-27 of the cycle (late secretion phase or late luteal phase), the “fading” corpus luteum decreases in size (10-15 mm), its echogenicity increases slightly, and the echostructure becomes more homogeneous. At the same time, the corpus luteum is often poorly visualized sonographically. In the absence of pregnancy, the blood supply to the corpus luteum begins to change by about 9 days after ovulation. The tissue of the corpus luteum begins to undergo luteolysis, the capillaries contract and reduce, which is characterized by a noticeable depletion of local blood flow.
During menstruation, the corpus luteum, as a rule, is no longer defined, or a fuzzy echo structure of increased echogenicity with a diameter of 2-5 mm (white body) remains in its place, which usually disappears without a trace during the next menstrual cycle. It has been proven that a non-passing white body in the form of a scar is preserved only after a gravid corpus luteum. Blood circulation in the vessels of the disappearing corpus luteum stops, and the vessels themselves disappear during the first three days of menstruation.

Follicles in the ovaries are essential for a woman's reproductive function. Ovulation - the release of an egg for subsequent fertilization - is impossible without their participation. The regular course of menstruation in most cases indicates the absence of violations in their work. Failure of their function occurs with pathologies of the sexual or endocrine sphere.

Description

Follicles are found in every appendage of a woman. All of them cannot be operational at the same time. Their maturation occurs gradually, during each menstrual cycle.

Structure

The follicle is an oocyte - a spherical cell. Its initial size does not exceed 25 µm. It is protected by a double layer of connective tissue and surrounded by epithelial cells. In its center is the nucleus and the germinal vesicle, from which the egg develops. The latter in a mature state is considered the largest cell in the body. Follicular fluid in the structure of the ovarian follicle is formed at the beginning of its growth. Such a bubble is highly likely to rupture in the current menstrual cycle.

purpose

The follicle is necessary to protect the egg from external influences. It provides her with favorable conditions for development. With the almost complete maturation of the female cell and with the beginning of the growth of the bubble in the first phase of the cycle, its fluid produces estrogen. When the latter reaches peak values, the level of luteinizing hormone increases sharply - it stimulates the rupture of the membrane for the release of the egg. This occurs in the middle of the cycle when the follicle in the ovary has matured and is called ovulation. This is where the functions of the bubble end.

In the future, the remnants of the shell are used to form the corpus luteum, which regulates the course of the last phase of the menstrual cycle.

Kinds

The types of follicles differ in their degree of maturity. This determines its diameter and the likelihood of a rupture in the current menstrual cycle.

Primordial

Primordial bubble is considered to be in a state of rest. This is the primary form of his development - it is in this state that he stays most of the time in the appendages of a woman. It contains an immature egg and does not increase in size. Its growth is possible in subsequent menstrual cycles.

Primary or preantral

Develops from the primordial. The dimensions of the primary sac slightly increase in comparison with the previous phase of its development. It occurs at the beginning of the menstrual cycle. Such vesicles contain a small volume of fluid, but are able to produce sex hormones.

Secondary, or antral

At this period of development, the fluid surrounding the egg is actively produced. More and more sex hormones are produced. Antral vesicles with a diameter of 7-11 mm are formed on the 8-9th day of the monthly cycle. With menopause, the number of such follicles in the ovary is minimized, sometimes they are completely absent.

Tertiary, or preovulatory, or mature

This species is most often called the dominant, or Graafian bubble, and is considered the peak of development. It reaches 18-22 mm in diameter, most often one or two of these follicles are located in one ovary. The Graafian vesicle is formed by the 14-16th day of the cycle. Its cavity contains a large volume of follicular fluid. The latter produces the maximum amount of estrogen, which contributes to the rupture of the membrane for the release of the egg.

The role of the dominant follicle

The functionality of the Graafian vesicle determines the likelihood of ovulation. In order for its shell to burst, it must produce the maximum amount of estrogen. The latter stimulate the pituitary gland, which produces luteinizing hormone, which triggers the process of ovulation. Under its influence, a stigma is formed on the vesicle - a protruding area in which the egg is located. It is at this point that the shell breaks.

The moment of ovulation is the most favorable time for conception. It lasts only a few days, and the egg itself is considered viable only for one day.

The dominant follicle is formed in the left or right ovary. In most women, the right appendage is considered more active - it is he who is also responsible for the production of sex hormones, the implementation of the reproductive function. The ovaries are able to work alternately - in this case, in one menstrual cycle, ovulation occurs in the left organ, and in the next - in the right.

Every month, an egg matures in the female ovary. It emerges from a special “bubble” that is formed even before birth, gradually matures, and then bursts. This "vesicle" is the dominant follicle. Sometimes it is called dominant, but doctors prefer the first option.

The size of the follicle by day of the cycle is very important. The ability of a woman to conceive depends on this factor.

Stages of development

What is a dominant follicle? This is a "leader" who has overtaken his "colleagues" in growth and development. Only he has a chance to burst and produce a mature egg, which will then be fertilized by a sperm. Physicians distinguish four stages of its development:

What should be the follicle on different days of the cycle: medical standards

If on ultrasound you were told that there is a dominant follicle in the left ovary (or in the right, it does not really matter), you need to ask about its size. Unfortunately, it happens that the size does not correspond to the day of the cycle, that is, a full-fledged egg does not mature.

The size of the follicle on the days of the cycle depends on the length of the menstrual cycle (namely, its first phase). The longer it is, the slower the egg matures, and the smaller it is on a certain day. For example, on the 10th day of the cycle, a follicle of 10 mm can be considered a relative norm if the monthly cycle is 35 days. But with a cycle of 28 days - this is no longer the norm.

If the cycle, on the contrary, is short, then the follicle will mature faster and reach its maximum size as early as 11-12 days.

Therefore, the rules that we give below should not be taken as absolute. Much depends on your individual characteristics. But for reference they will be useful. So, here are the norms for a healthy woman with a 28-day menstrual cycle.

From the 1st to the 4th day of the cycle on ultrasound, you can see several antral follicles 2-4 mm in size.
Day 5 - 5-6 mm.
Day 6 - 7-8 mm.
Day 7 - 9-10 mm. The dominant follicle is determined, the rest “lag behind” it and no longer grow. In the future, they will decrease in size and die off (this process is called atresia).
Day 8 - 11-13 mm.
Day 9 - 13-14 mm.
Day 10 - 15-17 mm.
Day 11 - 17-19 mm.
Day 12 - 19-21 mm.
Day 13 - 22-23 mm.
Day 14 - 23-24 mm.

So, from this table it can be seen that normal growth is about 2 mm per day, starting from the 5th day of the MC.

If the size is not correct

If the follicle is 11 mm on the 11th day of the cycle or 13 mm on the 13th day of the cycle, then this size is not the norm. This means that the egg matures too slowly and ovulation is hardly possible. The reason for this condition is most often in hormonal abnormalities: in the malfunction of the thyroid gland, pituitary gland, ovaries, or this entire “bundle”.

This condition requires additional examination (in particular, it is necessary to find out the level of hormones) and medical correction. Often gynecologists use hormonal drugs, but this is not always the case. In some cases, there are enough vitamins, drugs that improve blood circulation, herbal medicine, physiotherapy.

Experienced doctors know that many women do not ovulate every cycle. And they are not in a hurry to prescribe hormonal drugs, based on folliculometry for only one month. Perhaps in the next cycle, the egg will mature at the “correct” rate.

Sometimes anovulation (lack of ovulation) is due to natural causes:

Stress, fatigue, lack of sleep;
Malnutrition (strict diets, in particular low-fat ones);
Obesity or extreme thinness;
Hard physical work or exhausting sports training.

If you exclude these factors, there is a chance that ovulation will return on its own.

Size for ovulation

When the follicle bursts, at what size does ovulation occur? This usually happens on the 12-16th day of the menstrual cycle. With a 28 day cycle, ovulation occurs around day 14 (plus or minus two days). With a cycle of 30 days - on day 15.

At ovulation, the size of the follicle is 24 mm. The minimum figure is 22 mm.

In order for the follicle to burst, the coordinated action of various hormones in the woman's body is necessary. Namely - estradiol, LH, FSH. After ovulation, progesterone also enters the process.

How to understand that ovulation has occurred? The following methods will help you:

Folliculometry (a type of ultrasound). This is by far the most reliable way;
Ovulation tests. They are quite truthful and easy to apply, but they are not 100% accurate;
. In this case, it is necessary to build a BT schedule: the method is painstaking, not always reliable, but affordable.

Some girls (though not all) feel ovulation physically, here are the characteristic symptoms of a ruptured follicle:

Pulls the lower abdomen and lower back;
Small spotting in the middle of the cycle is possible;

Some experience irritation and increased fatigue. Others, on the contrary, a surge of strength and sexual energy.

Now the egg has 12-24 hours to meet the sperm. If this does not happen, she regresses, and after 12-14 days menstruation comes.

If the follicle does not burst

It happens that a follicle that has reached 22-24 mm in diameter does not burst, but turns into a follicular cyst. This is due to a deficiency of certain hormones in the body. This condition can be determined by ultrasound.

Sometimes the cyst is single, and it "resolves" itself. If this does not happen, then at first they try to eliminate it with medication. And only if it is large and does not decrease in size, then they resort to surgical intervention.

Sometimes there are many such cysts. They deform the ovaries, interfere with their proper work. This condition is called polycystic ovary syndrome and requires treatment.

If it turns out that the dominant follicle in the ovary matures, but does not burst, then doctors can apply hormonal drugs. For example, .

Where do twins come from

The "main" follicle is determined approximately on the 7-10th day of the cycle. All others shrink and naturally die off. But sometimes it happens that there are two “leaders” at once. In a natural cycle (that is, without the use of hormones to stimulate ovulation), this happens quite rarely - in one woman out of ten, and not every monthly cycle.

It happens that two dominant follicles in different ovaries (or in one - this is also possible) ovulate, that is, burst. And then there is a chance that both eggs will be fertilized. So, fraternal twins will be born.

Unlike twins (when one egg is fertilized by two sperm), twins are not the same, not the same person. They can be different sexes or the same sex, and look alike, like ordinary brothers and sisters.

So, the correct growth of the dominant follicle and subsequent ovulation are clear signs of women's health. And possible violations should alert you (and your doctor), but not scare. Indeed, in most cases, such deviations are successfully treated.

The follicle is a structural component of the female gonad, consisting of the egg and surrounding tissues.

Its persistence appears when the rupture of the capsule is not detected and the egg is not able to enter the uterine cavity. The dominant follicle is the one that will soon ensure the release of the egg into the uterine cavity.

Knowledge of information about what a follicle is helps to plan pregnancy and detect problems associated with conception.

In the female body, unique processes of maturation of follicles occur. They are laid during the period of embryonic development. Their approximate number in the womb is about 500 thousand.

By the beginning of puberty, their number decreases to 40 thousand, but not all of them fully mature. During the entire reproductive period, 500 peculiar egg sacs mature. The rest gradually atreziruyutsya, that is, fade away.

The process of their maturation from a biological point of view is extremely complex. It is influenced by a huge number of factors. It begins in the first phase of the female cycle. In order for this process to occur normally, the presence of follicle-stimulating hormone is required.

About 10 sacs with oocytes mature at one time, but only one of them will be dominant. An egg will come out of it on the 14th day.

Approximately on the 7th day of the cycle, using ultrasound, it is possible to visualize the growth of the capsule with the oocyte. Each is a few millimeters in size.

Daily ultrasound determines further growth. Reaching 2 cm in diameter, the follicle bursts, the germ cell is released and enters the fallopian tube. With a normal monthly cycle, this occurs on days 13-15. This may be accompanied by the following symptoms:

some soreness in the lower abdomen;
the amount of mucus from the female genital organs increases;
the basal temperature drops;
an increase in the amount of luteinizing hormone in the blood.

In one monthly cycle, one follicle matures in the female body. Rarely, 2 of them appear, which is not considered a pathology. Moreover, the release of multiple eggs greatly increases the chances of getting pregnant.

Kinds

There are such types of follicles:

primordial;
primary;
secondary;
tertiary.

Primordials are otherwise called resting. They are localized in the subcapsular zone. They are the smallest. Cells have a flat structure.

Primary otherwise are awakened. They are somewhat larger than primordial ones. Around the egg is a shell formed by protein substances.

Secondary follicles are slightly larger. They have stratified epithelium and several small fluid-filled chambers. Around it grows a shell inside the ovary - the theca. It appears in the ovary earlier than the theca and it is by it that the secondary capsule is identified.

Finally, the tertiary follicle (or Graafian vesicle) is mature. He has reached the highest level of development. It begins to press on the surface of the ovary. Its predominant volume is occupied by a cavity (capsule) filled with liquid and containing the oocyte. Surrounded by the theca.

What is a persistent follicle

A persistent follicle develops when the capsule does not rupture. The egg then remains in it because it does not enter the uterine cavity.

This process is pathological, because in the presence of persistence, fertilization cannot occur. A woman has difficulty getting pregnant.

The capsule can exist in the ovary for about 10 days. After the end of this period, a new menstruation begins. In some cases, a woman has a delay, and it can even last up to one and a half months.

Ovarian capsules dissolve on their own without taking additional drugs. Sometimes an ovarian cyst develops and requires treatment.

In the blood of women with persistent ovarian capsules, the amount of estrogen increases, the level of progesterone falls. The signs of ovulation disappear because the corpus luteum moves into the so-called behind the uterine space.

If the ovarian capsules exist for a long time, then there are delays in the monthly cycle. When menstruation occurs, a large amount of blood is released.

Note! Reproductive activity is associated with the balance of hormones. Due to the fact that the hormonal background is disturbed, persistence develops.

If a persistent follicle is found, pregnancy can be planned only under the supervision of a doctor. For this, the gynecologist determines the dominant capsule. This is possible with the help of an ultrasound examination.

It is done on the eighth day of the cycle. On day 12, the most suitable conditions for conception are created. For this, another ultrasound is prescribed.

The third examination is scheduled for the 18th day. The specialist checks for ovulation. A woman should carefully monitor the state of her body. After 10 days, a pregnancy test is allowed.

What is a dominant follicle

Every month, several egg capsules increase in the ovary. Then their growth stops, only one or very rarely - two continue to increase. He is dominant. The rest gradually regress.

Every day, the size of the dominant follicle grows by several millimeters. On the eve of ovulation, it reaches up to 18 - 20 mm in size. Under these conditions, an oocyte comes out of it, completely ready to accept the spermatozoon and form a zygote.

On ultrasound, the dominant follicle can be seen from the fifth day. It is rarely seen on the eighth day. At this time, it significantly outperforms other pouches.

This growth is due to the active influence of follicle-stimulating hormone. If it is not enough in the blood, then it does not reach the required values and even decreases. In this case, an ovarian cyst develops. After ovulation, a corpus luteum grows in the ovary.

Interesting! The dominant follicle is found most often in the right ovary. At present, it is not known exactly what this phenomenon is connected with. Often the corpus luteum can be found just in the right ovary. It is assumed that the phenomenon under consideration occurs due to the activation of the nervous system.

Norms

How many follicles should be in the ovary

The number of all dormant oocytes is laid down by nature at the stage of embryonic development. It is characteristic that before the onset of puberty, it decreases significantly. One egg is released every month.

The number of capsules with oocytes is determined by the day of the cycle. There may be several of them already a few days after menstruation. On the fifth day there can be up to 10 of them, and this is also the norm. After all, only one follicle will be dominant.

Deviations

In the absence of a dominant follicle, the release of the egg does not occur. This happens as a result of hormonal imbalance and some pathologies:

decreased production of follicle-stimulating hormone and increased excretion of luteinizing hormone;
regression due to hormonal disorders (including due to an increase in insulin content);
the presence of a persistent process;
the presence of an overripe sac;
the formation of a follicular cyst that grows in place of the dominant follicle (sizes exceed 2.5 cm during ultrasound examination);
polycystic ovaries;
pathological luteinization, when, without ovulation, the corpus luteum grows at the site of dominance.

Note! With persistence, the follicular sheath ruptures. The egg can be released into the abdominal cavity. Pregnancy in these cases does not occur.

All disorders of ovarian development require a thorough instrumental examination. Doctors prescribe hormonal tests for women, as the cause of deviations may be pituitary dysfunction, endocrine diseases.

Increased amount

If there are more than 10 follicles in the ovaries, they are called multifollicular. Polyfollicularity is also distinguished, that is, when a significant number of vesicles are detected on ultrasound. With an increase in their number several times, the diagnosis of "polycystic" is determined.

If the follicular elements are scattered around the entire periphery of the ovary, they become crowded. This interferes with dominance and all processes that promote conception.

This pathology develops due to stress and passes after a short time. The problem is treated if:

multifollicularity is caused by problems with the functioning of the endocrine glands;
there is a sharp weight loss or weight gain;
there were failures in the choice of oral contraceptives.

An insufficient amount

The lack of follicles is provoked by hormonal problems. You can find out the problem on an ultrasound scan on the seventh day. If there are less than 6, then the probability of conception is negligible. Finally, if there are less than 4, then pregnancy practically does not occur.

In some cases, women do not have follicles at all. The complete absence of menstruation signals the occurrence of problems with the female body. If they are absent for more than 3 weeks, you need to urgently visit a gynecologist.

Why the follicle does not mature

It may not ripen due to the presence of such reasons:

dysfunction of the female gonads;
disorders of the functionality of the endocrine system;
tumors of the pituitary gland, hypothalamus;
inflammatory pathologies of the small pelvis;
stress, nervous instability or depression;
early onset of menopause.

In these situations, there may be no follicles in the ovaries at all. It often happens that it does not reach a sufficient size so that an egg can come out of it.

Follicle growth table - size by day

The scheme of its growth can be visualized in the form of a table.

Stages of development

During its development, the follicle goes through several stages (phases).

Early phase

Several follicles grow. After reaching one of them (dominant) up to 24 mm in diameter, ovulation occurs.

luteal phase

The interval between ovulation and the start of a new cycle is called the luteal phase (or corpus luteum phase). After the Graafian bubble bursts, it begins to accumulate fats and pigments. This is how the corpus luteum develops. It produces progesterone, androgens, esradiol.

These substances activate the maturation of the endometrium. The uterus is preparing for the implantation of a fertilized oocyte. If pregnancy occurs, the corpus luteum continues to secrete progesterone until the placenta reaches a certain size and begins to produce it itself.

If pregnancy does not occur, then the corpus luteum is destroyed. The level of estrogen and progesterone gradually decreases, which contributes to the beginning of a new monthly cycle.

More about antral glands

These are glands that are highly likely to develop into a primordial follicle. In the future, he has a chance to evolve into a dominant one, from which the egg will then come out.

Potentially all antral glands have a chance to mature into a full-fledged oocyte. But there can be no more than 500 of them in a woman’s entire life. By the age of 50, a woman’s monthly cycle gradually fades away and reproductive function stops.

What does ultrasound show

Capsules with eggs can be easily detected on the screen during ultrasound diagnostics from the fifth day of the cycle. In the future, their dimensions increase. On the 7th day of the cycle, you can see which one is dominant.

On examination, empty follicle syndrome can be detected. This means that the ovary is not able to provide the exit of the gonad. Such a woman needs to get rid of infertility.

Ultrasound is completely safe for the body.

FAQ

How many days does the follicle mature

This process lasts only 9 days (plus or minus one). Provided that the hormonal background of a woman is stable, ovulation occurs on the 14th day of the cycle.

What can go wrong

With a hormonal disorder, too many follicles may be found in the ovary, or vice versa, too few. Sometimes it does not have a sex gland at all.

All these phenomena adversely affect the reproductive function of women.

If the size is not correct

The reduction of the follicle on the day of ovulation leads to the fact that the egg cannot come out of it. The woman cannot get pregnant. An increase in the Graaffian vesicle indicates a high probability of a cystic process. It also has a negative effect on conception.

If the follicle does not burst

In this case, one speaks of its persistence. This phenomenon is considered pathological and requires correction.

Where do twins come from

Fraternal twins appear from the fact that not one, but two eggs came out of the ovary.

Interesting! There are facts when twins were born from two men. This happens if a woman had sex with different men, and the fusion of the egg and sperm occurred on different days.

The follicle is the most important structural element of the ovary. The probability of an egg being released and a woman's chances of becoming pregnant depend on their number and development. The discrepancy between its size and number of indicators of the norm is a pathology. Such women should be treated for infertility.

Ask a Question!

You have questions? Feel free to ask any! And our in-house specialist will help you.

What is a dominant follicle? The answer to this question should be known to any woman who is interested in the structure of her body, and even more so at the stage of pregnancy planning. Find out the structure, functions, stages of maturation, size and other important and interesting points.

The female reproductive system is complex. The basis of future life is the sex cell, called the egg. Every month, she matures in the ovary, in order to then leave it and unite with the spermatozoon for the birth of a new life. Functions of protecting immature eggs (oocytes) are performed by the functional follicular cells surrounding them and located in the outer layers of the appendages, which later transform to fulfill their main purpose.

What day to do an ultrasound to find out if the follicle is maturing?

At the beginning of the menstrual cycle, follicular cells begin to rapidly develop and form vesicles. One of them grows faster than the others: it is dominant, and it is in it that the maturing and preparing for fertilization egg is located. At the same time, the rest pass into involution, that is, they return to their previous initial state.

Follicles are formed even before the birth of a girl.
The total number is about 1 million, but some are destroyed, and by the time puberty is completed, about 200-300 thousand remain. But for the entire reproductive period, no more than 500 pieces manage to fully mature, the rest are destroyed and excreted from the body.

Stages of development

Over the entire period of a woman's life, starting from birth, follicles go through several stages of development:

primordial stage. These are immature follicular cells that are laid down during the formation of a female fetus. They are very small and do not exceed 0.05 mm in diameter. Follicles capable of dividing are covered with epithelium and pass to the next stage.
Primary or preantral formations reach 0.2 mm in diameter. During the active puberty of a girl, the pituitary gland actively synthesizes folliculotropin, which accelerates the development of cells, strengthens their membranes and forms a protective layer.
Secondary or antral follicles increase in size up to 0.5 mm. Their total number is about 8-10. Under the influence of estrogens, the internal cavity begins to fill with fluid, which stretches the walls and provokes the rapid growth of bubbles. Secondary follicles, by the way, are considered temporary organs of the endocrine system that produce hormones.
As a rule, only one follicular formation passes to the next stage - the dominant one. It becomes the most voluminous and contains an almost completely mature and ready-to-fertilize egg. The vesicle consists of a large number of granulosa cells and is designed to provide reliable protection of the oocyte until the moment of ovulation. The remaining secondary follicles at this time synthesize estrogens, which ensure the rapid development of the main vesicle.
The tertiary or preovulatory vesicle is called the Graaffian vesicle. The follicular fluid completely fills its cavity, its volume increases a hundred times compared to the original. During ovulation, the vesicle ruptures and an egg is released from it.

Ripening in every menstrual cycle

From the beginning of the menstrual cycle, about 8-10 secondary follicles are formed in both ovaries. From about the eighth or ninth day of the cycle, the bubbles begin to fill with the liquid formed under the influence of estrogen synthesized by the female body. And already at this stage, the dominant follicle is noticeable: it is larger than the others, and this can be seen on ultrasound.

The bubble continues to fill with fluid, stretches and bursts at the time of ovulation. A mature egg is released, which will begin to move along the fallopian tube to the uterus to connect with the sperm. What day does the break occur? It depends on the duration of the menstrual cycle: if it lasts 28-30 days, then ovulation and, accordingly, the release of the egg from the burst follicle falls on the 14-16th day (the countdown is from the beginning of menstruation).

In place of the ruptured vesicle, a corpus luteum is formed - a temporary endocrine gland that actively synthesizes progesterone and ensures the preparation of the uterus for a possible pregnancy. The hormone produced makes the endometrium loose and soft so that the fetal egg can firmly gain a foothold in it and begin to develop.

Normal sizes

What is the size of the dominant follicle? It grows from the beginning of the menstrual cycle until ovulation, and its diameter is constantly changing. Consider the norms for different periods:

From the 1st to the 4th day of the cycle, all bubbles are approximately the same size - about 2-4 millimeters.
On the fifth day, the diameter reaches 5-6 mm.
On the 6th day, the bubble will grow to 7-8 mm in diameter.
By the seventh or eighth day, the follicle will reach a size of about 10-13 millimeters.
On the 9-10th day, the diameter increases to 13-17 mm.
By the 11-12th day, the size increases to 19-21 mm.
Before ovulation, the diameter can be about 22 mm.
During ovulation, the dominant follicle is 23-24 mm in size.

Normally, active growth begins approximately from the fifth day of the menstrual cycle and is about two mm per day.

In which ovary will the dominant follicle mature?

The dominant follicle can mature both in the left ovary and in the right one. In healthy women who do not have pathologies and diseases of the reproductive system, the appendages function fully and alternately. That is, if in the last cycle the mature egg left the follicle of the right ovary, then in the next menstrual cycle the oocyte will mature in the left appendage.

Scientists have noticed that most often the dominant follicle matures in the right ovary. Some researchers have associated this with a more active innervation of this side in right-handers, which are the vast majority of women. In other words, the right side is more functional, so the right appendage is better supplied with blood and oxygen, which stimulates the maturation of the bubble.

A rarer occurrence is two dominant follicles that have formed simultaneously in both ovaries. In this case, a multiple pregnancy is possible, and the born twins will be fraternal and not similar to each other. Theoretically, conception by two different biological fathers is possible if the follicles do not mature at the same time, and the eggs are released at different times with a certain interval.

Possible pathologies

Consider some deviations from the norm:

The dominant follicle is absent. This suggests that there will most likely not be ovulation in the current menstrual cycle. Every healthy woman has anovulatory cycles once or twice a year. If there is no ovulation for several months in a row, this is not normal.
Multiple follicles or the so-called multifollicular ovaries is a deviation that develops as a result of hormonal disorders. The dominant follicle may be absent or develop slowly, which will reduce the chance of conception.
The formation of cysts. The dominant follicle does not burst, overflows with fluid and stretches, forming a benign formation - a cyst (it can grow or regress on its own, that is, burst and disappear).
Atresia - slowing down, stopping the growth of the main vesicle and its subsequent death without the release of a mature egg.
Persistence. The dominant follicle reaches the desired size, but does not break and remains intact until the onset of menstruation. Conception becomes impossible.
luteinization. The corpus luteum begins to form when there is a whole follicle in the ovary.

These pathologies are visible on ultrasound and are caused by hormonal disruptions or diseases of the reproductive system.

The dominant follicle is essential for fertilization. But conception will occur if the bubble forms correctly, and a mature egg comes out of it. The information presented in the article will help to understand the mechanism of fertilization and identify some problems.

Discussion: 12 comments

Hello. Ultrasound of the follicle on the 13th 14th 15th day. Does it make sense to take 3 days in a row?

Yes, it makes sense to conduct an ultrasound every two to three days. Also for monitoring the endometrium to predict the date of ovulation.
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Hello, there was a delay of 2 weeks, then the menstruation went, but 2 days before them, the right ovary began to pull a little. This continued during menses. And now they have already ended, but the pulling pain has not disappeared. On the seventh day of the cycle, I went for an ultrasound, they said that everything is fine, in the right ovary the dominant follicle is 16 mm. They said that the pain is possibly associated with the growth of the follicle. Is this true, and when will the pain go away?

Hello, Natalia! Yes, this is usually due to the growth of the dominant follicle. If the pain will be of a prolonged nature, it is worth being examined for the presence of pathologies of the reproductive system.
Hello! 11 months have passed since the second birth. I am breastfeeding my baby. I drank Lactinet, menstruation came to the abolition. On the 15th day, she underwent follicullometry, the diagnosis was MFN, there was no dominant follicle. They were like that even before pregnancy. The cycle was extended, up to 50 days happened. Pregnant to cancel OK. Ovulation occurred at 16 dmc and 18 dmc Question: is ovulation possible in this cycle if there is no dominant follicle on ultrasound on the 15th day?
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1. Hello Amina! Unfortunately, ovulation is impossible without a dominant follicle, but don't worry, it may appear in the next cycles. Take care of your health, eat right and, if necessary, consult with your doctor additionally about resolving this issue. You may need to take tests, including hormones, as well as change your lifestyle to prepare the body for conception and pregnancy.
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Hello, help me figure it out, we plan to conceive a girl three days before the release of the egg. Cycle 29-31 days, 11 dc folliculometry showed a dominant follicle of 11 mm and the doctor said that the release of the egg will be on the 15-16th day. PA was at 13 dts early in the morning, exactly three days before the exit !!!, immediately the lower abdomen began to pull, the egg white increased (usually 2-3 days before O), and at 16-00 there were brown streaks on the linen, on 14 ds, pulling, throbbing pains continued and at 17-00 folliculometry showed that the follicle had begun !!! release fluid, the doctor said that free fluid was being scanned around the ovary and that ovulation had just begun. QUESTION: did it really start today (14 dts) or did it start on 13 dts, because If 13 then the Y chromosomes will definitely have time ((((, and if 14 then more than 30 hours have passed and the Y chromosomes died and X chromosomes remained (girls)))))

Hello Nina! It is worth trusting the doctor's words, and in your case, the probability of conceiving a girl is still greater, since the X chromosomes live up to 5 days. During the day or at the time of ovulation, there is a greater chance that there will be a boy.
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