Primary follicles are composed. Follicles - growth rates and maturation of follicles in the ovaries in women
Follicles in the ovaries are essential for exercise reproductive function women. 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 genital or endocrine sphere.
Description
Follicles are found in every appendage of a woman. All of them cannot be functional 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 microns. It is protected by a double layer connective tissue and is surrounded by epithelial cells. In its center is the nucleus and the embryonic vesicle, from which the egg cell 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. This bladder is more likely to rupture during the current menstrual cycle.
Purpose
The follicle is necessary to protect the egg from external influences. He provides her favorable conditions for development. With almost complete maturation of the female cell and with the onset of bubble growth in the first phase of the cycle, its fluid produces estrogen. When the latter reaches its 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.
Subsequently, the remnants of the membrane are used to form the corpus luteum, which regulates the course of the last phase of the menstrual cycle.
Views
The types of follicles differ in the degree of their maturity. This determines its diameter and the likelihood of rupture in the current menstrual cycle.
Primordial
A vesicle at rest is considered primordial. 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 grow 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. This happens at the beginning of the menstrual cycle. These vesicles contain a small volume of fluid, but are capable of producing sex hormones.
Secondary, or antral
During this period of development, the fluid that surrounds 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 8-9 day 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 type is most often called the dominant, or graaf 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 Graaf bubble 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 bubble determines the likelihood of ovulation occurring. 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 ovulation process. Under its influence, a stigma forms on the bubble - a protruding area in which the egg is located. It is in this place 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 forms in the left or right ovary. In most women, the right appendage is considered more active - it is he who is 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.
First, you need to figure out what the notorious follicles in the ovaries are, and how they can affect a woman's health. To begin with, we will conduct a small educational program on physiology.
The ovaries are the paired genitals of a woman. They are located in the pelvic area. Their function is generative. Simply put, the ovaries are responsible for the development and maturation of female reproductive cells. In addition, they produce sex hormones and are endocrine glands. This organ consists of connective tissue (scientifically - stroma) and cortical substance. The follicles in the ovaries mature there. The work of the ovaries is strictly cyclical.
What are follicles?
Each follicle consists of an egg, which is surrounded by a layer of epithelial cells and two layers of connective tissue. All of them go through several stages of development: primordial, preantral (or primary), antral (respectively, secondary) and preovulatory (tertiary). In the primordial stage, the size of the follicle is 50 µm; its development can be suspended until the girl's puberty. At the next stage, a cavity is formed, which contains the follicular fluid. As they mature, the follicles in the ovaries produce androgens, which penetrate the follicular membrane and are transformed into estrogens. Just before ovulation, the follicle
increases significantly in size; About 24 hours before the start, an increased release of estrogen begins, which stimulates the release of luteinizing hormone. The follicle wall breaks and the egg comes out - this is ovulation.
For almost the entire life of a woman, follicles are formed in a continuous flow. Of these, 99.9 percent do not ovulate, we can say they die. In medicine, this process is called "atresia". One, maximum two or three follicles undergo ovulation.
Follicle development
It is possible to understand that the follicles in the ovaries have begun to develop by the growth of the oocyte. In this case, the resumption of meiosis does not occur. But the formation of cytoplasmic products begins, which will subsequently be consumed.
early embryo. The glycoprotein covers the outer surface of the oocyte, in parallel with this, the oocyte is covered in several layers by granular cells. Thus, it turns out something like a capsule.
The next stage in the development of the follicle is the formation of the cavity. This cavity is filled with follicular fluid, which appears due to the secretion of granular cells and plasma transudate. As the cavity is formed, the cells of the capsule divide into cells of the inner and, accordingly, the outer shell. This is exactly the time when the follicle grows vigorously: from one millimeter it grows to sixteen. It is during this period that the cavity greatly increases in size due to the fact that the cells of the capsule and granular cells continue to proliferate. The cavity at this stage makes up most of the preovular follicle. At the same time, the oocyte is still surrounded by granular cells and undergoes minor changes in the further growth process. Follicular ovaries cannot cause infertility. Strictly speaking, this is not even a diagnosis, but a certain state of the body. However, it needs adjustment, which can be carried out under the supervision of a physician.
The follicles in the ovaries are part of the female reproductive system that allows you to conceive a child. Deviations from the norm in the development of these elements are fraught with unpleasant pathologies, and sometimes infertility.
Ovarian ultrasound. Follicles
The ovarian cycle consists of two phases - follicular and luteal. We are interested in the first one.
The follicle contains the egg, which is surrounded by a layer of epithelial cells and two layers of connective tissue. It depends on how reliably the egg is protected and whether it is possible to save it, whether a woman can become pregnant and bear a baby. Thus, the main thing functional significance these structures - to provide the egg with protection from negative influences different factors which is very important during pregnancy. The maturation of one such formation is carried out in a month.
All follicles in the ovaries contain an egg that is not fully matured. It will finally mature only after the fertilization process.
Another, no less important function of such formations is the production of the hormone estrogen. In the fairer sex, follicles are continuously formed throughout their lives. Of these, 99.9% die, do not ovulate. And only one, rarely 2-3 follicles undergo ovulation.
Dominant follicles and their role
The dominant follicle is the largest and most mature element that protects the egg cell ready for fertilization. Before ovulation, he is able to reach two centimeters in size. Usually located in the right ovary.
Reaching a state of maturity and being under the influence of hormones, the dominant follicle ruptures, the ovulation process occurs. The egg cell rapidly moves to the fallopian tubes. If the dominant element does not mature, then there will be no ovulation.
There are situations when the maturation of dominant formations in both ovaries occurs simultaneously. There is no need to worry about this. Most likely, such a woman has every chance of conceiving twins after ovulation. However, this is possible only if the dominant elements in both the right and left ovaries ovulate both at once. This is not common.
The number and rate of follicles in the ovaries
Follicles in the ovaries are counted based on the day of the start of the menstrual cycle. If multiple follicles are found a couple of days after the end of menstruation, this is not considered a deviation.
The middle of the cycle will be marked by one or two elements that will exceed the rest in size. At the end of the cycle, only one will remain large. An egg should come out of it, which at that time is ready for fertilization. The rupture of the education itself is manifested by the beginning of the menstrual cycle.
Find out more about the number of follicles in the article.
Deviations from the norm
If the quantitative composition of the follicles in the ovary exceeds 10, it is considered to be a violation. It will be possible to diagnose such a pathology only by the results of an ultrasound scan. Moreover, their number does not change at all over the course of the cycle. During ultrasound examination there are a large number of small bubbles. In the event that their number increases several times, the woman is diagnosed with polycystic disease. characterized by the formation of multiple follicular formations along the periphery.
Polycystic disease can interfere with dominant formation, ovulation, and conception. The development of such problems can provoke nervous disorders and stress. In this case, polycystic disease does not require special treatment, and the deviations will bounce back easily.
However, in some cases, the underdevelopment of follicular elements requires special therapy. These include the following:
- if oral contraceptives were selected incorrectly;
- when endocrine problems occur;
- when recruiting excess weight or, conversely, drastic weight loss.
If the follicles in the ovary are above normal, this does not necessarily mean that polycystic disease has developed or is a signal of some kind of ailment. It is likely that the reason for this was overwork, stress, constant emotional overstrain. In this case, after the first ovulation, their number is normalized.
Since obesity can provoke follicular failure and lead to an imbalance in the functioning of the ovaries, women are advised to monitor their diet and pay due attention to physical activity.
Every woman must regularly visit a gynecologist-endocrinologist. This will allow timely identification of pathology and promptly begin to treat it.
To establish why follicles in the ovaries are formed with abnormalities from the norm, only a gynecologist is able after passing certain tests and a special examination.
Persistent follicle
The question of what is a follicle is asked by those who have a similar diagnosis. Pathology means that the formation of the dominant element proceeded as it should until the very moment when it was supposed to burst. This did not happen and the egg, accordingly, does not come out. Regardless of where the persistent follicle on the right or left ovary was diagnosed, ovulation does not occur. The cause of the disease may lie in hormonal disruptions in a woman, in cases where the male hormone is present in excess. If you do not intervene in such a process in a timely manner, then the development of infertility is not excluded.
The essence of the treatment comes down to hormone therapy.
At the initial stage, reception is carried out medicines who will have to suppress male hormones in the body.
The second stage involves the introduction of hormones intramuscularly. In addition, it is necessary to carry out massage procedures, laser therapy, ultrasound effects on the pelvic organs.
Lack of follicles
However, it sometimes happens that the follicular structures on the ovaries are completely absent. The reason for this lies in the early onset of menopause or malfunctioning of the ovaries. In this case, the doctor prescribes hormonal treatment... You can find out about the presence of such a problem by irregularities in the menstrual cycle.
Follicles in the body of the fairer sex should produce a certain amount. In the event that more or less of them are formed, this is always considered a deviation. Sometimes everything can end with the development of infertility. Therefore, when faced with menstrual irregularities, a woman should immediately contact a doctor to establish the cause and prescribe the necessary treatment.
Hello dear readers of the blog site.
I want to tell you about how the follicles ripen in the female ovary, what the follicle cycle is. As he matures, becomes dominant, ovulates.
How many situations I see when a woman literally does not get out of the ultrasound room, tracking the growth of the follicle and hoping for ovulation. And if there is no ovulation, then the doctor will definitely recommend hormonal stimulation to induce it.
To make a competent, informed decision about whether you need to stimulate ovulation, you need to have at least a little idea of what is happening in the ovaries. And how will this intervention affect them, and it will be serious, because the entire endocrine system will be involved.
I have met situations when after stimulation of ovulation, the potential of the ovaries decreased tenfold. For example, AMG () before stimulation was 0.9 ng / ml, and after it became 0.01.
The ovaries are the main organs for a woman, this is our only source, the only "battery". And if it is "discharged" ahead of time, then there will be no one to make claims, except to itself.
What is a follicle?
The follicle is an integral part of the ovary. It consists of an egg cell, which is surrounded by epithelial cells and connective tissue.
How many follicles a woman has, depends on her ability to give birth to a child, her health, beauty, youth, efficiency and quality of life.
Where do follicles come from?
Follicular formation begins in the early prenatal period. First, the so-called primary, or indifferent gonad (sex gland) is laid in the fetus. Then follicles begin to form from her cells.
Until 7-8 weeks, the fetus has no signs of sex, and only after this period does sexual differentiation begin, and it becomes clear whether a boy is growing or a girl.
The cycle of a follicle is the stages of its development, stages of its growth
As you understand, everything starts from the stage of reproduction, from cell division (mitosis), which begins in the indifferent gonad of the embryo.
After this, the development of the follicle continues. He enters the growth stage, which is subdivided into the small and big stature, and then - in the stage of maturation.
This occurs in several stages - the formation of a primary, secondary, tertiary (dominant) follicle, then - the phase of the corpus luteum and white body. But let's look at everything in order.
Breeding stage
The cells of the sex cords of the primary gonad in the girl begin to divide and form 5-7 million primary follicles. This is called the multiplication stage, and the follicles that form are called primordial.
There are so many primordial follicles (from hundreds of thousands to millions) that outwardly it is somewhat reminiscent of the eggs that are formed in fish during spawning.
The number of primordial follicles that form in a little girl up to 5 months of intrauterine development depends on the love and passion of the parents, their age and state of health.
The stage of reproduction occurs in the girl's ovaries only in the prenatal period, and is never renewed again. This is one of the key differences between the male and female body.
Women have only that which is laid only during the stage of follicular reproduction. Further, the follicles are only wasted. In men, the reproductive cells are constantly renewed, until old age.
Primary (preantral) follicle formation - small growth stage
Until about 7-8 months of intrauterine development, a part of the primordial follicles is, as it were, "re-preserved", and the process of their further development begins.
They turn into primary (preantral) follicles - they undergo the first stage of meiosis - the formation of sex cells with a half set of chromosomes. It is these cells that are needed for fertilization and the beginning of a new life.
In the DNA of maturing eggs, crossing over occurs, that is, DNA strands change fragments with each other. Therefore, the primary follicles are already different from all cells of the body, and they must be protected from the watchful eye of immunity, which seeks to destroy everything foreign. Sometimes this does not work, and its own immunity can destroy the supply of primary follicles.
Not all primordial follicles can go through this stage - most of they die at this stage. If a girl had, for example, 5 million primordial follicles, then at this stage there may be only a million of them. The rest disappear, die, this process is called follicular atresia.
By the way, atresia can threaten not only primordial follicles. At any stage of maturation, death and disappearance of follicles can occur.
The speed and extent of atresia depends on many factors. It may happen that the primary potential is great, but pregnancy, childbirth, the development of the girl in the first years of her life were accompanied by illness and stress, and the follicles will die, as if providing themselves with what happens to the girl, giving energy for this.
But back to intrauterine development. Those follicles that have passed the first stage of the maturation process can be said to be lucky, there are not so many of them left in comparison with the primary amount that is at the stage of reproduction.
At the stage of preantral follicle formation, meiosis stops for many years. Until puberty, the remaining primordial and primary (preantral) follicles will be at rest, not responding to any fluctuations in the hormonal background. It is known that some follicles in the resting stage can be up to 50 years old!
Secondary (antral) follicle formation - large growth stage
The resting stage ends and the follicle cycle resumes starting at puberty. Every month from several tens to several hundred preantral follicles begin to activate and turn into an antral follicle, which already looks like a small vesicle.
The maturation period of the secondary (antral) follicle lasts up to 300 days. Not all primary follicles turn into secondary ones, most of them die along the way. Atresia (death) awaits the developing sex cell at any stage.
Tertiary follicle formation - continued large growth
The tertiary follicle (Graaf's vesicle or dominant follicle) is formed under the influence of FSH (follicle-stimulating hormone).
Up to this point, the follicles were insensitive to pituitary hormones, the main control was for anti-Müllerian hormone (AMH), which inhibited their development.
Nothing like a large number of antral (secondary) follicles pass into the stage of the tertiary follicle. The rest - die, undergo atresia.
The bubble increases, the egg inside it goes through all the stages of meiosis, but not yet to the end. The egg accumulates nutrients, she prepares to exit the follicle and to complete the development cycle.
The tertiary follicle stage lasts about 6 days and ends when the egg is ready to ovulate. Outwardly, this stage can be seen by the fetal secretion of the cervix that appears in a woman (stretchable like the white of a raw egg).
The granular cells of the follicle produce estrogens, and gradually there are more and more of them. The more estrogens, the less the pituitary gland produces follicle-stimulating hormone. The pituitary gland reduces the stimulation, receiving the message from the follicle that the egg is almost ready. This is called "negative Feedback".
But there is also a positive feedback - the more estrogen is produced in the follicle, the higher the level of luteinizing hormone (LH) becomes.
Already a few hours (about 12 hours) before ovulation, granular cells begin to "turn yellow", luteinize, and begin to produce progesterone. That is, the corpus luteum begins to work.
By the way, he can be seen on an ultrasound scan and decide that ovulation has occurred. But this has not happened yet, and the woman may draw the wrong conclusions about the stage of the cycle.
In addition, the study itself (ultrasound) is quite capable of blocking ovulation, and an already finished egg, having passed such a long way, will not come out.
Normally, the growth of LH continues following the growth of estrogens, and at "peak" LH values, the follicle ruptures and the egg is released into abdominal cavity- ovulation.
As a rule, several follicles are trying to mature to the level of the Graafian vesicle. They all produce estrogens. But only one reaches full maturity. The rest, as always, are atreticated.
Follicle maturation stage
The period or stage of maturation begins at the moment when the maturing egg is in the oviparous tubercle of the tertiary follicle (in the cumulus) and is surrounded by a radiant crown. The cycle of the follicle is coming to an end, but not yet completed, meiosis is not complete, half of the set of chromosomes has not yet formed.
The ripening stage is the shortest of all. It begins at the peak of LH, about 12 hours before ovulation, and ends only after fertilization, about 1-2 days.
Meiosis ends completely only after ovulation, provided that fertilization has taken place. If it was not there, then the follicle cycle remains incomplete, the egg dies about 12-24 hours after ovulation.
Fertilization takes place in fallopian tube... The penetration of the sperm into the egg is the starting point for the resumption of meiosis; it ends with the formation of a half set of chromosomes.
At this time, the egg cell already contains sperm chromosomes, and they merge, forming a zygote - the first cell from which a child will grow. In fact, the end of the follicle cycle is the first hours of human life.
After ovulation, a corpus luteum forms at the site of the tertiary follicle
The egg is no longer there. Her cycle is over. And the follicle itself, as we know it, disappears. In its place, a corpus luteum is formed, in which the hormone of motherhood, progesterone, is produced.
The corpus luteum exists normally from 10 to 16 days, sometimes, extremely rarely, up to 12 weeks in the form of a cyst of the corpus luteum. This does not require any intervention, the corpus luteum cyst disappears by itself.
If fertilization does not occur, then the corpus luteum turns into a white (whitish) body, in which androgens are produced - the raw material for future estrogens. Androgens, in principle, are produced in the theca cells of atretic follicles, they stimulate the development of new portions of maturing follicles.
The woman is menstruating, and a new portion of secondary (antral) follicles enters the stage of development of the tertiary follicle. They are ready by this time, ripened for a long time, remember? - up to 300 days! And everything is repeated from the beginning.
If fertilization has occurred, then the corpus luteum exists for 5-7 weeks, giving way to the chorion. It is the chorion, and then the placenta, that take on the function of producing progesterone, which is very necessary for nourishing and warming the child.
We spend our follicular supply all our lives
How many children does a woman give birth to? One or two, maximum three. Earlier they gave birth to more. This means that the entire follicle cycle is completed in a woman's life only a few times. At the start, we have millions of opportunities, only a few reach the finish line.
All dying follicles give up their enormous potential, and we live on this potential. Our ovaries are constantly "discharged" throughout life, releasing the latent power of possible human lives that did not happen.
Medicine now widely uses the stimulation of ovulation, agitates young women to donate eggs, convincing - it's okay, there are millions of follicles.
But this is not the case. Behind one matured and ovulated follicle are hundreds of thousands of dead "along the way." Our "battery" is discharged during these manipulations many times faster, like a phone in the cold.
The climax occurs when there are about a thousand primary follicles. It's up to you if you want to bring this time closer using hormonal contraceptives, ovulation stimulation, and more.
Stay young and healthy, take care of your ovaries.
I wish you happiness. :)
Best regards, Elena Volzhenina.
One of the structural components of the female reproductive system, formed by the ovaries, is the follicle. In a woman's body, the ovaries perform two main functions: the production of sex hormones and the formation of sex cells.
Under the ovarian membrane is the cortical substance, the tissue of which is formed by follicles. Their differentiation is carried out according to the degree of maturity; at the same time, 4 types of cells are distinguished:
- Immature.
- Primary.
- Secondary.
- And also tertiary follicles.
Immature (primordial) follicles consist of a nucleus (oocyte) and one layer of epithelial cells. On the inner surface of the ovary, such cells are in the majority, since few follicles develop further and reach maturity.
At the next stage of formation, some follicles increase in size, acquiring a new layer of cells and microvilli around the oocyte, and become primary follicles.
Further, the follicles continue to grow, their tissue becomes denser, resulting in the formation of an outer shell. The epithelium becomes multi-layered, while it secretes a secret that contains estrogens. At this moment, the follicle is considered secondary, and the oocyte inside it shifts to one of the poles; capillaries and connective tissue begin to form.
After filling the cavity with follicular fluid, the follicle becomes tertiary, or mature, and is called the "graaf bubble". Such a follicle becomes rather large - dominant, and protrudes through the surface of the ovary. The rest of the cells do not continue their development, and usually no more than 1-2 bubbles per cycle ripen in a woman's body.
Folliculogenesis and conception
After the graaf bubble begins to slowly move towards the exit, due to a sharp surge in the release of hormones, its size increases until it reaches 1.5–2 cm in diameter. This is due to the filling of the follicle cavity with liquid, which begins to thin and stretch its walls. During this period, the nucleus has already been transformed into an egg, which is located at the most extreme point of the upper pole of the follicle.
The day before ovulation, the ovaries begin to produce and release an increased amount of estrogen into the bloodstream. Due to this, the concentration of luteinizing hormone increases, which, in addition to thinned walls, also provokes ovulation. The top point of the follicle wall ruptures, and the egg is released from its cavity.
In the event that ovulation does not occur, a follicle of another type is formed from the graafian bubble - a cystic one. It can leave the body with menstruation, or it can remain in the ovary, subsequently forming a cystic formation in it.
After a woman's most important cell for conception - the egg - has left the follicle, it quickly changes its appearance and content. Capillaries and granulosa cells increase their cytoplasm; also a large number of lipid cells and yellow pigments appear in the formation, therefore at this stage it is called the "yellow body". The altered follicle produces inhibin, estradiol, androgens and progesterone, which enter the general bloodstream.
If conception occurs during ovulation, the corpus luteum begins to actively develop and continues to play the role of a hormonal gland, releasing progesterone, which is extremely important for preventing contraction of the walls of the uterus and normal bearing of the fetus. The corpus luteum dies only when the placenta is fully formed - by the 10-15th week of the development of the unborn child. In the event that pregnancy has not occurred, the corpus luteum loses its functions and, after passing through the luteal phase of the cycle, comes out with menstrual bleeding.
Disorders in the formation and development of follicles
Disorders of the ovaries and their performance of the main reproductive function - the formation of follicles, as well as failures in the processes of follicle maturation and ovulation are among the most frequent reasons infertility. The reason for these phenomena is often a violation of the hormonal background of a woman. For example, with insufficient production of follicle-stimulating hormone (FSH), the maturation of the graafian vesicle cannot occur. There are also situations when the synthesis of luteinizing hormone (LH) increases, which causes an increase in the concentration of androgens in the blood and stops the development of follicles in the initial stages.
To correct hormonal disorders, treatment with special drugs is carried out; after careful monitoring of folliculogenesis in the absence of ovulation, its stimulation with hormone injections can be prescribed, which is carried out only under the supervision of a doctor.
Disruptions in inhibin production often lead to diseases such as polycystic ovary disease. In this case, temporary infertility is possible, which should be treated with conservative or surgical methods.
Folliculogenesis is well monitored using conventional ultrasound machines. For this, a study is carried out on the 8-10th day from the beginning of the cycle, when the follicle is already visible, which subsequently becomes dominant.
By the approximate time of ovulation, another ultrasound diagnostic procedure is performed, and recommendations are made about a favorable time of conception.