A woman loses most of the follicles from cycle to cycle. Every month, the body begins preparing for pregnancy - it starts the mechanism and completes it with the onset of menstrual bleeding. When a woman is planning a pregnancy, she needs to know what the follicle is, how to determine the onset of ovulation, so that fertilization occurs successfully.
Definition and the process of education in the body
In order to understand what a follicle is, you need to imagine a pear-shaped sac, a bubble. This term is also found in other branches of medicine, however, in this context, it will be considered the female reproductive system. Since in this case we are talking about the ovaries, it is worthwhile to understand that the follicle contains an egg.
The process of their occurrence in the female body begins even in that period when the embryo develops in the womb and is identified by gender. In other words, as soon as the laying of the female genital organs at the embryo has occurred (7-8 weeks of gestation), the process of development of the follicles necessary for the normal functioning of the female body in the future begins.
Key parameters: stages of growth and development
The development of the follicle begins with mitosis - cell division even at the stage of embryo formation. This is just the first stage, in the future the follicle goes into the stage of active growth. It consists of several stages:
- Small stature.
- A big increase.
- Maturation.
In the process of development of the follicle passes the primary period, secondary and tertiary, ending in the formation of a yellow and white body. By themselves, they are necessary for the body to produce hormones and the formation of germ cells. At the initial stage, the follicle consists of a nucleus and epithelial cells. In the process of development, it is covered with a new layer and microscopic villi. Condensing, the tissue (epithelium) becomes multilayered and releases the hormone estrogen. Inside the oocyte is shifted to one of the walls, capillaries, connective tissue are formed. At the tertiary stage, the follicular vesicle is filled with liquid, its dimensions become much larger than before, and it protrudes outward, through the wall of the ovary.
What is the stage of reproduction
At the stage of cell division, the active formation of follicles occurs, the number of which reaches about 5-7 million. They are also called primordial. They look like microscopic eggs. The degree of maturity of the parents, their state of health directly affect their number in the body of the girl. Unlike the male body, the reproduction of primordial follicles occurs only during the intrauterine development of the female fetus. The process stops around the fifth month. In the male, the germ cells are continuously restored, and again resume their growth.
After birth, puberty, the body of a young girl can only spend that supply of follicles, so that it was formed earlier.
Small stage
For those who do not have a medical education and who have not delved into the intricacies of the structure of their body, it is most likely unclear what the follicle is and why the first (preantral) stage is so called. Primary cells begin their next developmental stage at 7-8 months of gestation of the female fetus. Preantral follicles go through the stage of formation of germ cells having a half set of chromosomes. The structure of the follicle is as follows: follicular cell, oocyte, stromal cells. They will be necessary in the future for the process of fertilization and the beginning of a new pregnancy.
In extremely rare cases, you can even talk about pathologies, immunity cells take follicles for foreign and destroy them completely. This is because the DNA strands of a ripening egg exchange fragments with each other. Most primordial follicles at this stage die, and only one million remain of the entire initial (ovarian) stock (for example, 4-5 million). This phenomenon is also called atresia, it also applies to other stages of development.
Before puberty, the follicles will be at rest. They do not develop, but can die, giving their energy to restore women's health. Therefore, excessive pain in the children's period in a girl, stress, etc., can adversely affect their number. In medical practice, there are rare cases when the primary follicles were in the waiting stage for up to 50 years.
Antral follicle
From the moment when the girl is faced with puberty, transitional age, the development of follicles begins again. Every month, from a dozen to hundreds of preantral small cells are converted into antral, resembling a small vesicle. If you look at the days of the cycle, follicles on the 7-8th day begin to actively produce estrogens. The cavity in which the follicular fluid is located increases. The epithelium of the cell becomes bilayer, and the size of the follicle reaches 10-15 mm.
The development cycle can last up to 300 days. Most primary follicles die at this stage and only a small fraction will go to the second stage.
A big increase
Under the influence of follicle-stimulating hormone (FSH), a graaf bubble, or tertiary, dominant follicle in the ovary is formed. Previously, he was not susceptible to the hormones secreted by the pituitary gland, since its growth was inhibited by the antimuller hormone.
The bubble increases in size, and in the meantime, the egg goes through all stages of development, accumulates nutrients to leave the follicle. This period lasts up to six days, and the end of it means a willingness to ovulate. Externally, a woman can determine in her her onset of discharge in the form of egg white.
A large number of estrogens produced by granular follicle cells in the ovaries stimulate a decrease in the pituitary gland of follicle-stimulating hormone. The so-called "negative feedback" occurs. However, estrogen activates an increase in the level of luteinizing hormone (LH). Before the formation of a graaf bubble, there can be several growing follicles in the ovary, but only one remains fully mature, the rest die.
Before ovulation begins, granular cells begin to luteinize (turn yellow), and progesterone production is active. At the maximum stage of estrogen and LH growth, the follicle breaks, and the egg is released into the abdominal cavity. This process is called ovulation.
Ripening period
The shortest stage of all is the follicle maturation. What happens in the body during this period and how long does it last? It is customary to count the beginning before ovulation (12 hours), and the end in a day or two after fertilization. If it happened successfully and two cells - male and female met, then cell division continues and the follicle development cycle ends with the formation of a half set of chromosomes.
The egg, when merged with the sperm, receives the necessary half of the chromosomes, the first cell is formed - the zygote. From this moment begins the development of the human embryo.
Yellow and white body
After the egg has left the follicle, a yellow body forms in its place. It is necessary for the production of the right amount of progesterone, which preserves and promotes the development of pregnancy. His life expectancy is from 10 to 16 days, in some cases up to 12 weeks. This applies to the usual, not pregnant state of a woman. With successful fertilization, it persists for up to seven weeks, after its function replaces the chorion and then the placenta.
In the absence of pregnancy, the corpus luteum becomes white, as the production of androgens starts. They stimulate the growth of new ripening cells. Menstrual bleeding begins and the process of development of secondary follicles starts again. The body goes through the same stages as in the last cycle in anticipation of successful fertilization.
By the time the woman begins the menopause, about a thousand follicles remain in her ovaries, the size of which has remained at the secondary stage.
Persistence
Violation of the follicular apparatus - this is persistence, which can cause bleeding or delayed menstrual bleeding. It is customary to talk about a persistent follicle in the ovary when it is mature, dominant, but there is no rupture and the egg does not come out. Therefore, one cannot talk about the onset of fertilization and pregnancy. As the likelihood of events - the formation of a cyst. In order to help her burst, the doctor may prescribe injections with progesterone.
Ultrasound Diagnostics
For a woman planning a pregnancy, it is important to know not only what the follicle is, but also how many should be normal for determining a successful cycle. During folliculometry by ultrasound, the diagnostician can determine their number. On the 6-7th day from the start of a new cycle within the normal range - up to 10 pieces. From the 8th to the 10th day of the cycle, one remains dominant, while the others die. The maximum follicle size can reach two cm.
In the case when there are two fully matured cells, and they are both fertilized, this means that the woman will have twins. This phenomenon is more likely to occur when the ovaries are stimulated by hormonal or other drugs. A large number of follicles does not at all mean that a woman is more likely to become pregnant. If an amount greater than ten is determined by ultrasound, then this phenomenon is called polyfulicularity, and the diagnosis is polycystic.
Less than four is a sign that the chances of a successful conception are very few. In this case, artificial stimulation, the appointment of special drugs may be required.