What is the dominant follicle?

Folliculogenesis is a cyclic process occurring in the ovaries under the control of the nervous and endocrine system. The main mechanism of it is the transformation and transformation of the follicle into a mature egg.

The main stage of folliculogenesis is the formation of a dominant (basic) follicle.

Dominant follicle is formed by successive stages:

- the beginning of the formation of many small antral follicles ,

- growth and development of small follicles,

- maturation of the dominant follicle,

Ovulation.

It can be said that a mature dominant follicle is an ovum that should vomit. Thus, it becomes clear that in the presence of all the above stages of follicle formation, eventually, ovulation occurs, i. E. Pregnancy is possible.

The formation of small follicles begins with the first days of the menstrual cycle. However, their growth begins only in the hormone-dependent phase, which occurs immediately after the completion of the luteal phase. At the same time, the amount of estradiol and progesterone decreases, but the amount of follicle-stimulating hormone (FSH) increases.

It should be noted that the dominant follicle is affected by many factors that can lead to its death. However, the female body is designed in such a way that all its processes are aimed at preserving the egg and fertilizing it. Therefore, the dominant follicle "protects" the epidermal growth factor and the transforming growth factor (TGF).

After 5-7 days after the beginning of the menarche, small follicles begin to form. They are also called tertiary or antral. They are quite a large number - about 10 pieces. This phase of folliculogenesis is called early proliferation or the onset of the formation of small antral follicles . The diameter of these small formations does not exceed 5 mm. They are located in the form of "beads" on the periphery of the ovary. For some time, some of the follicles have increased in size and are gaining strength.

Consequently, the dominant follicle is formed after about 10 days of the menstrual cycle, and at this time its dimensions reach 15 millimeters. Other follicles, which could not gain the right mass, regress and die. As a result, we can conclude that the dominant follicle may not be one. When two or more ovules mature, which subsequently become fertilized, a multiple pregnancy develops. This process is not common, but cases such are fixed. Most often this is the iatrogenic cause: hormone-based drugs, oral contraceptives or IVF. But the physiological reason for the appearance of twins and triplets is not excluded.

To the immediate moment of ovulation, the dominant follicle should reach a diameter of about 20 millimeters (maybe more). The place of the follicle should form a yellow body a little smaller than its predecessor.

If fertilization does not occur, within a week after the release of the ovum from the ovary, the yellow body begins to decrease in size - it regresses. By the time of rejection of the endothelium of the uterus, the yellow body, as a rule, dies off, and in its place can only remain a site of disturbed echogenicity.

Speaking about folliculogenesis, one can not help but dwell on the concept of "persistent follicle".

Persistent is called the follicle, which passes all stages of folliculogenesis, except for immediate ovulation. What reasons can lead to this phenomenon, is not fully understood. However, doctors often assume persistence as a variant of the norm, unless, of course, it is not constantly repeating.

Sometimes it happens that the persistent follicle turns into a small ovarian cyst. For patients who have a cyst, observation is necessary. If this process does not cause complaints, then treatment is not required.

As a rule, persistent follicles burst during ovulation, but it is almost impossible to conceive under such a situation, because the endometrium of the uterus is too thin for implantation.