A follicle is a bubble formation in human organs. The ripened follicle contains a finished egg.
During menstruation, the follicles in the ovaries begin to grow, the egg matures and becomes prepared for fertilization.
Sex hormones (progesterone, estrogens, androgens) are considered steroids, in their appearance cells of the outer and inner layers, granulosa cells of the follicle take part.
Of the "female" ailments, various ovarian diseases are very common. Since the ovaries are located deep in the abdominal cavity, any disorders that are associated with them do not have any external signs or symptoms of the disease.
Every month, a woman has follicles in the ovaries, inside which the egg begins to develop. In the middle of the cycle, the follicle breaks, and the egg that is inside begins to move to the uterus. It happens that this does not happen, this situation is considered the most common cause of cysts.
On the surface, the ovaries are surrounded by a protein membrane formed by a dense fibrous connective tissue, which is covered with peritoneal mesothelium. The surface of the mesothelium is covered with microvilli. With all this, the mesothelial cells have a cubic shape. The cortical substance is located directly under the protein coat, and the cerebral substance in the ovaries is deeper.
The cortical substance is formed by follicles of varying degrees of maturity, which are located in the connective tissue stroma. There are 4 types of follicles in the ovaries:
Primordial follicles in the ovaries consist of an oocyte surrounded by a layer of flat cells and a basement membrane. This is the main type of follicle in the ovaries of a woman who has not reached puberty.
Primary follicles. As the size of the follicles increases, so does the size of the reproductive cell itself. Near the cytolemma, a shiny, secondary zone appears, outside of which are cubic follicular formations. A characteristic feature of such follicles is the appearance of a shiny zone consisting of glycosaminoglycans and mucoproteins produced by an oocyte or follicular epithelium.
Secondary follicles in the ovaries. The growth and size of the follicle is caused by the growth of the follicular single-layer epithelium and its degeneration into a multilayer. The epithelium produces follicular fluid, which accumulates in the cavity of the follicle and includes steroid hormones.
Such follicles are called secondary. Ovocyte in them is no longer becoming, although they due to the accumulation of follicular fluid in them significantly increase.
Mature follicles in the ovaries, which have reached their greatest development and include one cavity filled with follicular fluid, are considered tertiary.
The bubbly (or tertiary) follicle can reach such a size that the surface of the ovary protrudes. A further increase in the size of the bubble filled with follicular fluid can lead to thinning and stretching of its outer and protein membranes of the ovary.
If the doctor sees an ovary enlarged in volume and many small follicles - more than 12 pieces, then the follicular ovaries can be diagnosed.
A large number of follicles does not reach maturity, but passes through atresia - a specific restructuring that has a destructive nature. Cells begin to atrophy in the granular layer, and the shell cells in this case not only do not die, but, on the contrary, actively multiply and, by hypertrophy, in appearance and form become similar to luteal cells in the corpus luteum, which are in full bloom. So an atretic body appears, outwardly a bit like a yellow body, however, characterized by the presence in the center of a shiny zone of oocyte.