Dominant follicle 26. What are the optimal follicle sizes during ovulation? Internal processes of follicle evolution

A follicle is a component of the ovary that is surrounded by connective tissue and consists of an egg. The follicle contains the nucleus of the oocyte - the “germinal vesicle”. The oocyte is located inside a glycoprotein layer surrounded by granulosa cells. The granulosa cells themselves are surrounded by a basement membrane, around which there are cells - theca.

Internal processes of follicle evolution

The primordial follicle consists of oocytes, stromal cells, and follicular cells. The follicle itself is practically invisible, its size is on average 50 microns. This follicle is laid before birth. It is formed thanks to germ cells, they are also called oogonia. The development of primordial follicles is promoted by puberty.

A single-layer ordinary follicle consists of a basal plastic, a follicular cell forming a transparent membrane, and a multilayer primary follicle consists of a transparent membrane, an inner cell, and granulosa cells. During puberty, follicle-stimulating hormone (FSH) begins to be produced. The oocyte grows and is surrounded by several layers of granulosa cells.

The cavitary (antral) follicle consists of a cavity, an inner layer of Theca, an outer layer of Theca, granulosa cells, and a cavity containing follicular fluid. Granulosa cells are already beginning to produce progestins. The diameter of the antral follicle is on average 500 microns. The gradual maturation of the follicle with the formation of its layers gives rise to the production of female sex hormones, including estrogen, estradiol, and androgen. Thanks to such hormones, this follicle turns into a temporary organ of the endocrine system.

A mature follicle (Graafian vesicle) consists of an outer layer of the theca, an inner layer of the theca, a cavity, granulosa cells, a corona radiata, and an ovarian tubercle. Now the egg is located above the oviductal tubercle. The volume of follicular fluid increases 100 times. The diameter of a mature follicle varies from 15 to 22 mm.

What size should a follicle be?

It is impossible to answer this question unequivocally, since the size of the follicles changes during the menstrual cycle. Follicles are fully formed by the age of fifteen on average. Their sizes are determined only with the help of ultradiagnostics.

We will most accurately analyze the norm of follicle size by day of the menstrual cycle.

In the first phase of the menstrual cycle (days 1–7 or the beginning of menstruation), the follicles should not exceed 2–7 mm in diameter.

The second phase of the menstrual cycle (8-10 days) is characterized by the growth of follicles, their diameter generally reaches 7-11 mm, but one follicle can grow faster (it is usually called dominant). Its diameter reaches 12 - 16 mm. On the 11th -15th day of the menstrual cycle, normally the dominant follicle should increase every day by 2 - 3 mm, at the peak of ovulation it should reach a size of 20 - 25 mm in diameter, after which it bursts and releases the egg. Meanwhile, other follicles simply disappear.

This is what the follicle growth pattern looks like. This is repeated monthly until pregnancy occurs. For a more visual and understandable definition, we provide you with a table by which you can understand whether your follicles are maturing normally.

What is a dominant follicle?

A dominant follicle is considered to be a follicle that is ready for successful ovulation. During natural ovulation, it stands out due to its size. As we said earlier, although all the follicles begin to grow, only one of them (in rare cases - several) grows to a size of 22 - 25mm. It is he who is considered dominant.

Generative function as a priority. Let's figure out what it is.

There are two components to the function of the ovaries.

The generative function is responsible for the growth of follicles and the maturation of an egg capable of fertilization. Hormonal function is responsible for steroidogenesis, which changes the uterine mucosa, helps not to reject the fertilized egg and regulates the hypothalamic-pituitary system. It is generally accepted that the generative function is a priority, so if it fails, the second one loses its abilities.

At what follicle size does ovulation occur?

Ovulation is the release of an egg from a ruptured mature follicle. In this case, the size of the follicle during ovulation becomes 15 - 22 mm (in diameter). To make sure that you have a full-fledged follicle by the time you ovulate, you need an ultrasound examination.

Empty follicle syndrome

Currently, two types of this syndrome are described: true and false. What differentiates them is their hCG level. We can say that thanks to IVF technology, scientists have examined under a microscope the phenomenon when the follicle is “empty”.

According to statistics, in women under 40 years of age, this syndrome occurs in 5 - 8% of cases. The older a woman gets, the higher the number of empty follicles. And this is no longer a pathology, but a norm. Unfortunately, it is impossible to accurately and immediately diagnose this syndrome. To do this, you will need to completely eliminate damage to the ovaries (structural abnormalities), lack of ovarian response to stimulation, premature ovulation, hormonal imbalance, defects (pathologies) in follicle development, premature aging of the ovaries. That is why there is no such diagnosis as “empty follicle”.

But scientists have found the reasons that accompany the development of the syndrome. Namely: Turner syndrome, incorrect time of administration of the hCG hormone, incorrect dose of hCG, incorrectly selected IVF protocol, incorrect technique for collecting and washing the material. As a rule, a competent reproductive specialist will carefully collect anamnesis before making this diagnosis.

Polycystic ovary syndrome

Otherwise it is called Stein-Leventhal syndrome. It is characterized by impaired ovarian function, absence (or altered frequency) of ovulation. As a result of this disease, follicles do not mature in a woman’s body. Women with this diagnosis suffer from infertility and lack of menstruation. It is possible that menstruation occurs rarely - 1-3 times a year. This disease also affects the disruption of hypothalamic-pituitary functions. And this, as we wrote earlier, is one of the functions of the proper functioning of the ovaries.

Treatment here can proceed in two ways. These are surgical and medicinal (conservative). The surgical method often involves resection with removal of the most damaged area of ​​ovarian tissue. This method leads to the restoration of a regular menstrual cycle in 70% of cases. For the conservative method of treatment, hormonal drugs are mainly used (Klostelbegit, Diana-35, Tamoxifen, etc.), which also help regulate the menstrual process, which leads to timely ovulation and the desired pregnancy.

Folliculometry: definitions, possibilities

The term folliculometry is commonly understood as monitoring a woman’s reproductive system during the menstrual cycle. This diagnostic allows you to recognize ovulation (whether it happened or not), determine the exact day, and monitor the dynamics of follicle maturation during the menstrual cycle.

Monitoring the dynamics of the endometrium. For this diagnosis, a sensor and a scanner are used (it’s more common for us to call it ultrasound). This procedure is absolutely identical to the procedure for ultrasound of the pelvic organs.

Folliculometry is prescribed to women to determine ovulation, evaluate follicles, to determine the day of the cycle, for timely preparation for fertilization, to determine whether a woman needs ovulation stimulation, to reduce (in some cases increase) the likelihood of multiple pregnancies, to determine the reasons for the absence of a regular menstrual cycle , detection of diseases of the pelvic organs (fibroids, cysts), to control treatment.

This procedure does not require strict preparation. It is recommended only during these studies (usually an ultrasound is done more than once) to exclude from the diet foods that increase bloating (soda, cabbage, brown bread). The study can be carried out in two ways: transabdominal and vaginal.

Values ​​of indicators of norm and pathology of follicle development

We described the normal indicators both by day and during ovulation above (see above). Let's talk a little about pathology. The main pathology is considered to be the lack of follicle growth.

The reason could be:

• in hormonal imbalance,
• polycystic ovary syndrome,
• dysfunction of the pituitary gland,
• inflammatory processes of the pelvic organs,
• STD,
• neoplasms,
• severe stress (frequent stress),
• breast cancer,
• anorexia,
• early menopause.

Based on practice, health workers identify such a group as hormonal disorders in a woman’s body. Hormones suppress the growth and maturation of follicles. If a woman has a very small body weight (plus there are also STD infections), then the body itself recognizes that it cannot bear a child, and the growth of the follicles stops.

After normalizing weight and treating STDs, the body begins to grow follicles correctly, and then the menstrual cycle is restored. During times of stress, the body releases hormones that contribute to either miscarriage or stopping the growth of follicles.

After complete emotional recovery, the body itself begins to stabilize.

Ovulation stimulation

Stimulation is usually understood as a complex of hormonal therapy that helps achieve fertilization. Prescribed to women diagnosed with infertility for IVF. Infertility is usually diagnosed if pregnancy does not occur within a year with regular sexual activity (without protection). But there are also contraindications for stimulation: impaired patency of the fallopian tubes, their absence (except for the IVF procedure), if it is not possible to conduct a full ultrasound, low follicular index, male infertility.

The stimulation itself occurs using two schemes (they are usually called protocols).

First protocol: increasing minimum doses. The purpose of this protocol is the maturation of one follicle, which excludes multiple pregnancies. It is considered gentle, since its use practically eliminates ovarian hyperstimulation. When stimulated with drugs according to this scheme, the size of the follicle usually reaches 18 - 20 mm. When this size is reached, the hCG hormone is administered, which allows ovulation to occur within 2 days.

Second protocol: reduction of high doses. This protocol is prescribed to women with low follicular reserve. But there are also requirements for it that are considered mandatory indications: age over 35, previous ovarian surgery, secondary amenorrhea, FSH above 12 IU/l, ovarian volume up to 8 cubic meters. When stimulating this protocol, the result is already visible on days 6-7. With this protocol there is a high risk of ovarian hyperstimulation.

The female body periodically undergoes restructuring (natural cyclical changes) due to the influence of hormones that control complex mechanisms relating to its reproductive system (the set of organs that ensure the process of fertilization). For pregnancy to occur, a mandatory condition must be met - the growth and normal development of ovarian follicles, which act as a kind of “containers” for already

Interpretation of the concept of “follicle”

This is a small anatomical formation that looks like a gland or sac filled with intracavitary secretion. Ovarian follicles are located in their cortex. They are the main reservoirs for the gradually maturing egg.

Initially, the follicles in quantitative terms reach significant values ​​in both ovaries (200 - 500 million), each of which, in turn, contains one germ cell. However, during the entire period of puberty, women (30-35 years old) reach full maturity only 400-500 specimens.

Internal processes of follicle evolution

They occur in their sacs and are characterized by the proliferation of granulosa or granular cells that fill the entire cavity.

Then the granular cells produce a fluid that pushes and pushes them apart, directing them towards the peripheral parts of the follicle (the process of filling the internal cavity with follicular fluid).

As for the follicle itself, it increases significantly both in size and volume (up to a diameter of 15-50 mm). And in terms of content, it is already a liquid with salts, proteins and other substances.

On the outside, it is covered with a connective tissue membrane. And it is precisely this state of the follicle that is considered mature, and is called the Graaffian vesicle (in honor of the Dutch anatomist and physiologist Rainier de Graaff, who discovered this structural component of the ovary in 1672). A mature “bubble” interferes with the maturation of its colleagues.

What size should a follicle be?

With the onset of puberty (14-15 years), he completely completes his development. It is considered normal if during the follicular phase, when the menstrual cycle begins, several follicles mature in both ovaries, of which only one reaches a significant size, which is why it is recognized as dominant. The remaining specimens undergo atresia (reverse development). The product of their vital activity is estrogen - a female sex hormone that affects fertilization, childbirth, as well as calcium content and metabolism.

The dominant follicle, whose size increases on average by 2-3 mm every day, reaches its normal diameter (18-24 mm) at the time of ovulation.

Generative function as a priority

On the inside, the mature follicle is lined with multilayered epithelium; it is in it (in the thickened area - the oviductal tubercle) that a mature egg capable of fertilization is located. As mentioned above, the normal follicle size is 18-24 mm. At the very beginning of the menstrual cycle, a protrusion (resembling a tubercle) on the surface of the ovary is observed.

Due to a number of hormonal disorders, this gap may be absent, and therefore the egg does not leave the ovary and the ovulation process does not occur. It is this moment that can become the main cause of infertility and dysfunctional uterine bleeding.

Folliculometry: definition, possibilities

This is an ultrasound diagnostic test, through which the process of development and growth of follicles can be monitored. Most often, women suffering from infertility or menstrual irregularities resort to it. The manipulation in question allows us to track the dynamics of ovulation using ultrasound.

At the beginning of the menstrual cycle, it becomes possible to observe the process of endometrial growth, and in a later period - the evolution of the follicle. So, you can determine the exact size of the follicles by the days of the cycle.

When is folliculometry required?

This diagnostic test allows:

The significance of indicators of norm and pathology of follicle development

At the very beginning of its evolution, the indicator in the “norm” status is the size of the follicle with a diameter of 15 mm. Further, as mentioned earlier, it increases by 2-3 mm per day.

Many women are interested in the question: “What is the size of the follicle during ovulation?” Normally it is considered to be about 18-24 mm. Then the yellow body appears. At the same time, the level of progesterone in the blood is necessarily increased.

A single ultrasound is not able to build a complete picture of the development (maturation) of the follicle, since it is especially important to monitor each individual stage.

The main pathologies that disrupt the maturation of follicles are:

1. Atresia - involution of a non-ovulated follicle. To be precise, after formation it develops up to a certain point, and then freezes and regresses, thereby ovulation never occurs.

2. Persistence - the preservation of the virus, when it is still functionally active, in tissue culture cells or an organism beyond the period characteristic of an acute infection. In this case, the follicle forms and develops, but it never ruptures, as a result of which it does not increase. This form of anatomical formation is maintained until the very end of the cycle.

3. Follicular cyst is a type of functional formation localized in the ovarian tissue. In this situation, the unovulated follicle does not rupture, it continues to exist, and fluid most often accumulates in it, and subsequently a cyst larger than 25 mm in size is formed.

4. Luteinization - the formation of the corpus luteum, which sometimes forms without rupture of the follicle, which subsequently also develops. This situation is possible if there has been a previous increase in LH levels or damage to the ovarian structure.

Follicle sizes by cycle day

From the very first days of the next cycle, using ultrasound, you can notice that in the ovaries there are several antral anatomical formations in question, which will subsequently grow. Their increase is due to the influence of special hormones, the main ones being FGS and estradiol. Provided that their level corresponds to the established norm for the content of these substances in the blood, a woman most often experiences stable ovulation, and anovulatory cycles are observed no more than twice a year.

After the size of the follicles during stimulation according to the first scheme reaches a diameter of 18 mm (at 8 mm), triggers (drugs that simulate the release of LH) are administered. Then, after the administration of hCG, ovulation occurs approximately two days later.

The second manipulation scheme is applicable mainly to women who have a low and low probability of effect from small doses of FSH.

Mandatory indications for this manipulation:

• female age over 35 years;
• FSH value over 12IU/l (on days 2-3 of the cycle);
• ovarian volume up to 8 cubic meters. cm;
• secondary amenorrhea and oligomenorrhea;
• the presence of ovarian surgery, chemotherapy or radiotherapy.

A visible result should appear by the sixth day. A significant side effect affecting the ovaries during this ovulation is the risk of their hyperstimulation syndrome. If the next ultrasound reveals follicles in the ovaries whose diameter exceeds 10 mm, the doctor regards this as a signal to carry out preventive procedures for this syndrome.

Control ultrasound examination

It is necessary to confirm ovulation using transvaginal ultrasound. This is as important as the monitoring itself. It was previously mentioned what the size of the follicle is before ovulation (18-24 mm in diameter), however, even when the required size is reached, the capsule may not break through, and the mature egg will not be released into the abdominal cavity. A control ultrasound is performed 2-3 days after the estimated moment of ovulation.

At this session, the doctor will check the condition of the ovaries for signs of ovulation:

• the dominant follicle is absent;
• corpus luteum present;
• there is some fluid in the space behind the uterus.

It is important to note that if a specialist conducts a control ultrasound at a later period, he will no longer detect either fluid or the corpus luteum.

Finally, it would be useful to once again answer the question: “What is the size of the follicle at ovulation?” This dominant anatomical formation at the time of ovulation matures to a size of approximately 18 - 24 mm in diameter. It is worth remembering that the size of the endometrium and follicles change depending on the day of the menstrual cycle.

A woman's ability to conceive and bear a child is determined by the number of follicles in the ovary. The expectant mother must have an idea of ​​the processes occurring in the reproductive organs. Knowing how many follicles should be in the ovaries normally will allow her to receive timely medical help if danger arises.

Follicles are structural components of the ovary, consisting of an egg and 2 layers of connective tissue. The number of these elements depends on the age of the woman. A pubescent girl has about 300,000 follicles ready to produce eggs. In a woman aged 18-36, about 10 elements mature every 30 days. At the very beginning of the cycle, 5 structural components can mature simultaneously, then 4, then 3. By the time of ovulation, there is only one of them left.

No need to worry

Normally, the number of follicles in the ovaries is determined by the day of the cycle. If, a couple of days after the end of your period, numerous follicles are present in the ovaries, this is normal.

The middle of the cycle is characterized by the appearance of 1-2 elements, the size of which is slightly different from the rest. Then a mature egg begins to emerge from the largest follicle. The size of this element allows us to call it dominant.

The number of follicles in the ovaries can be determined using ultrasound of the appendages. This procedure is carried out using a vaginal sensor. So the specialist finds out the number of antral follicles, the size of which varies between 2-8 mm. Their number is interpreted as follows:

• 16-30 is normal;
• 7-16 - low level;
• 4-6 - low probability of conceiving;
• less than 4 - probability of infertility.

An ultrasound scan most often reveals 4 to 5 follicles. Less commonly, 2 to 3 elements are visualized. In preparation for in vitro fertilization, a woman is prescribed hormonal stimulation of follicle maturation. Therefore, during the course of the study, from 4 to 6 mature elements may be discovered.

Size by day

With each critical day, there is an increase in the volume of follicles by day. Until day 7, their size ranges from 2-6 mm. Starting from the 8th, active growth of the dominant follicle is observed. Its size reaches 15 mm. The remaining elements gradually decrease and die. On days 11-14, an increase in follicles is observed. The volume of a ripe element often reaches 2.5 cm.

Deviation from the norm

It is important to know what level of follicles is considered a deviation from the norm. More than 10 elements are called . Sometimes during the examination many levels of miniature bubbles are detected. This phenomenon is called polyfolicularity.

If more than 30 elements are detected during the study, then the woman is diagnosed. This pathology is an obstacle to the formation of a dominant follicle. Ovulation and conception become questionable. If the disease develops against the background of stress or emotional stress, then treatment is not carried out. Medical help is needed when polycystic disease is provoked by:

1. Sharp weight loss.
2. Rapid gain of extra kilos.
3. Endocrine pathologies.
4. Incorrect selection OK.

The follicular component may be completely absent or stop in its development. Often there is a delay in its formation or delay in maturation.

If the number of follicles decreases, the woman also has problems conceiving. In order to find out the exact cause, the doctor prescribes an ultrasound examination. It is carried out when the follicular apparatus is in the antral stage. This is observed on days 6-7 of the cycle. The main provocateur of a decrease in the number of follicles is a decrease in hormonal levels.

In some women, follicle maturation occurs during lactation. If their size varies from 6 to 14 mm, this indicates that a mature egg will soon be released. Then ovulation will occur and your period will begin.

Development of dominant and persistent follicle

Uneven development of follicles in the ovaries is often observed. Some women reveal the presence of dominant elements in both organs. If they ovulated at the same time, this suggests that the woman can conceive twins. But this is rarely seen.

You need to sound the alarm when a follicle is identified. This often indicates improper development of the dominant, which prevents the egg from being released. Over time, it appears against this background.

Persistence occurs on the left or right. The main provocateur is the increased production of male hormone. Improper treatment leads to infertility.

To resuscitate the reproductive system, a woman is prescribed hormonal treatment. Therapy is carried out in stages. From days 5 to 9 of the cycle, the woman is prescribed the use of pharmacological drugs. 8 days before the arrival of the critical days, the patient is given hormone injections. The duration of such treatment varies from 4 to 7 days. In the interval between the use of drugs, stimulation of the pelvic organs is carried out. The woman is prescribed laser therapy and massage.

Main reasons for absence

When there are no follicles in the ovaries, we can talk about hormonal imbalance. Other factors that provoke the lack of follicle development include:

• natural early menopause;
• improper functioning of organs;
• surgical early menopause;
• decreased estrogen production;
• pituitary gland disorders;
• the presence of an inflammatory process.

Presence of single elements

Some women are diagnosed with ovarian depletion syndrome. Due to the cessation of organ functioning, a woman cannot conceive and bear a child. Single follicles develop poorly, ovulation is absent. This leads to early menopause. The main cause of this condition is excessive physical activity. The risk group includes professional athletes and women doing men's jobs. Other reasons include menopause, a sharp jump in weight, and hormonal imbalances. This phenomenon is often observed in women who adhere to a very strict diet.

Timely treatment helps many women. You can prevent the development of a dangerous disease by calculating your menstrual calendar. If the cycle is irregular and often goes astray, then you should immediately consult a doctor.

Over the course of a woman's entire life, the ovaries produce a strictly defined number of follicles. Deviation from the norm does not always indicate the occurrence of a dangerous pathological process. But if a woman ignores this signal from the body, this will lead to dire consequences.

Ask a question!

Do you have any questions? Feel free to ask any questions! And our staff specialist will help you.

What is a dominant follicle? Any woman who is interested in the structure of her body, and especially who is at the stage of planning a pregnancy, should know the answer to this question. Find out the structure, functions, stages of maturation, size and other important and interesting points.

The female reproductive system has a complex structure. The basis of future life is a reproductive cell called an egg. Every month it matures in the ovary, then comes out of it and unites with sperm to give birth to a new life. The 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 are later transformed to fulfill their main purpose.

On what day should I 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 egg maturing and preparing for fertilization is located. At the same time, the rest go into involution, that is, they return to their previous initial state.

Follicles are formed even before a girl is born.
The total number is about 1 million, but some are destroyed, and by the time puberty ends, about 200-300 thousand remain. But during 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:

1. Primordial stage. These are immature follicular cells that are formed during the formation of a female fetus. They are very small and do not exceed 0.05 millimeters in diameter. Follicles capable of reproducing by division are covered with epithelium and move to the next stage.
2. Primary or preantral formations reach 0.2 mm in diameter. During 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.
3. Secondary or antral follicles increase in size to 0.5 mm. Their total number is about 8-10. Under the influence of estrogen, the internal cavity begins to fill with liquid, 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.
4. As a rule, only one follicular formation passes into the next stage - the dominant one. It becomes the most voluminous and contains an egg that is almost completely mature and ready for fertilization. The vesicle consists of a large number of granulosa cells and is designed to provide reliable protection for the oocyte until ovulation. At this time, the remaining secondary follicles synthesize estrogens, which ensure the rapid development of the main vesicle.
5. The tertiary or preovulatory vesicle is called a graafian vesicle. Follicular fluid completely fills its cavity, its volume increases a hundred times compared to the original. During ovulation, the sac ruptures and an egg is released.

Maturation in each 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 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 an ultrasound.

The bubble continues to fill with fluid, stretches and bursts at the moment of ovulation. A mature egg is released, which will begin to move along the fallopian tube into the uterus to connect with the sperm. On what day does the breakup occur? This 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 occurs on the 14-16th day (counting 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 prepares the uterus for a possible pregnancy. The hormone produced makes the endometrium loose and soft so that the fertilized egg can firmly establish itself 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. Let's look at the norms for different periods:

• From the 1st to the 4th day of the cycle, all bubbles have approximately the same size - about 2-4 millimeters.
• On the fifth day, the diameter reaches 5-6 mm.
• On the 6th day, the vesicle 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 has a size of 23-24 millimeters.

Normally, active growth begins around 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 in both the left and right ovaries. In healthy women who do not have pathologies or diseases of the reproductive system, the appendages function fully and alternately. That is, if in the last cycle a 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 the dominant follicle most often matures in the right ovary. Some researchers have associated this with more active innervation of this side in right-handed people, which is the vast majority of women. In other words, the right side functions more, so the right appendage is better supplied with blood and oxygen, which stimulates the maturation of the vesicle.

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

Possible pathologies

Let's look at some deviations from the norm:

• There is no dominant follicle. This suggests that there will most likely not be ovulation in the current menstrual cycle. Every healthy woman experiences anovulatory cycles once or twice a year. If you don't ovulate for several months in a row, this is not normal.
• Multiple follicles or so-called multifollicular ovaries are 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.
• Cyst formation. The dominant follicle does not burst, fills with fluid and stretches, forming a benign formation - a cyst (it can grow or regress on its own, that is, burst and disappear).
• Atresia is a slowdown, 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 rupture and remains unchanged until the onset of menstruation. Conception becomes impossible.
• Luteinization. The corpus luteum begins to form when there is a whole follicle in the ovary.

The listed pathologies are noticeable on ultrasound and are caused by hormonal imbalances or diseases of the reproductive system.

A dominant follicle is necessary for fertilization. But conception will occur if the vesicle is formed correctly and a mature egg is released from it. The information presented in the article will help you understand the mechanism of fertilization and identify some problems.

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Discussion: 12 comments

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

Answer

1. Yes, it makes sense to conduct an ultrasound every two to three days. Also for monitoring the endometrium to predict the date of ovulation.

   Answer

Hello, there was a delay of 2 weeks, then my period came, but 2 days before it my right ovary began to pull a little. This continued during menstruation. And now they are over, but the nagging pain has not disappeared. On the seventh day of the cycle I went for an ultrasound, they said that everything was fine, in the right ovary there was a dominant follicle of 16 mm. They said that the pain may be related to the growth of the follicle. Is this true and when will the pain go away?

Answer

1. Hello, Natalya! Yes, this is usually due to the growth of a dominant follicle. If the pain continues for a long time, it is worth undergoing an examination for pathologies of the reproductive system.

   Hello! 11 months have passed since the second birth. I am breastfeeding my child. I took Lactinet and my periods stopped. On the 15th day I did a folliculometry test, the diagnosis was MFN, there was no dominant follicle. They were like this even before pregnancy. The cycle was extended, up to 50 days. I became pregnant after discontinuing OK. Ovulation occurred at 16 dmc and 18 dmc Question: is ovulation possible in this cycle if there is no dominant follicle on the ultrasound on the 15th day?

   Answer

   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 to resolve this issue. You may need to take tests, including hormone tests, and also change your lifestyle to prepare your body for conception and pregnancy.

      Answer

Hello, help me figure it out, we are planning to conceive a girl three days before the release of the egg. Cycle 29-31 days, 11 dc foliculometry showed a dominant follicle of 11 mm and the doctor said the egg would be released on days 15-16. PA was at 13 dc early in the morning, exactly three days before the release!!!, immediately the lower abdomen began to tighten, the egg whites increased (usually this is 2-3 days before O), and at 16-00 there were brown streaks on the underwear, at 14 dc, the nagging, throbbing pain continued and at 17-00 foliculometry 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 dc) or did it start on 13 dc, because... If there are 13, then the Y chromosomes will definitely make it ((((, and if there are 14, then more than 30 hours have passed and the Y chromosomes have died and X chromosomes (girls))) remain

Answer

1. Hello Nina! You should trust 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 during ovulation, there is a greater chance of having a boy.

   Answer

As is known, in the cortical layer of the ovary of the intrauterine fetus there is a huge number of primary follicles, and each follicle contains one (very rarely two) germ cells. According to available not entirely accurate calculations, the total number of primary follicles contained in both ovaries is at least 200,000.

Each primary follicle can reach full development and produce an egg cell suitable for fertilization. However, during the entire period of a woman’s puberty, which lasts an average of 30–35 years, only 400–500 follicles fully mature. All the remaining primary follicles die sooner or later. The death of follicles is usually preceded by incomplete, stopped development. In this case, the egg cell dies first; then the follicular, or granular, epithelium (granulosis) undergoes fatty degeneration and vacuolization, the follicle fluid is absorbed, its cavity becomes empty and is obliterated by the connective tissue that grows in it. This process of death of follicles that have begun to mature is called follicular atresia.

Follicular atresia begins during intrauterine life, apparently under the influence of maternal sex hormones. By the end of the girl's second year of life, the process of follicular atresia usually stops for a number of years. Later, at approximately 7-10 years of age, it resumes again. In this case, the waste products of developing, albeit prematurely dying, follicles enter the tissue layers and, through a neurohumoral route, influence the development of the female type. In this regard, a special role is played by the specific female sex hormone produced by the follicles - estrogen hormone (follinulin).

Follicular development begins with the division of follicular cells and their transformation from initially flat to cubic and then highly prismatic. Proliferating cells, now called granular cells, fill the entire follicle. As development continues, the fluid secreted by the granular cells begins to push them apart and push them toward the peripheral layers of the follicle. Inside the follicle, a cavity is formed filled with follicular fluid. The follicle itself becomes large in volume, stretches, and from the compact formation it was before, turns into a hollow formation called a mature follicle, graafian follicle or graafian vesicle. A developing follicle inhibits the maturation of other follicles. Follicles that have begun to mature undergo atresia, with the exception of one (or rarely 2-3 follicles), which reaches full development during puberty and turns into a mature follicle. This usually occurs by the age of 14–15 years.

The size of the follicle (mature) reaches 1 cm. It is surrounded on the outside by fibrous connective tissue (theca folliculi), consisting of two layers: the outer thin layer of dense connective tissue is bled, thinned and finally ruptured. The Graafian follicle is opened and the mature egg is released. The maturation of the egg and its release from the Graafian follicle is the second of the two main functions of the ovary - the generative function.