Function of the ovaries

Synonyms

Ovary, ovaries (pl.), Ovary, ovary, oophoron

English: ovary

function

The ovaries are the woman's reproductive organs. On the one hand, the egg cells mature and are released into the fallopian tubes. On the other hand, the ovary is a production site for hormones (Estrogens, progestins).

These processes are controlled by the pituitary gland (pituitary gland), which releases hormones in a certain time schedule (secreted) and thus directs the ovarian cycle. These hormones are the pituitary gonadotropins FSH (= follicle-stimulating hormone) and LH (luteinizing hormone).

Illustration ovaries

1. Ovary -
   Ovary
2. Basic tissue of the ovary -
   Stroma ovarii
3. Mature vesicle follicles -
   Folliculus ovaricus tertiarius
4. Corpus luteum -
   Corpus luteum
5. Uterine cavity -
   Cavitas uteri
6. Cervix -
   Ostium uteri
7. Ovarian ligament -
   Ligamentum ovarii proprium
8. Fallopian tube fringed funnel -
   Infundibulum tubae uterinae
9. Fallopian tubes -
   Tuba uterina
10. Ovarian artery -
    Ovarian artery

You can find an overview of all Dr-Gumpert images at: medical illustrations

The follicle in the Ovaries the woman will all be together before the birth educated. No new follicles appear after birth.
At birth, a woman has 1 to 2 million follicles in both ovaries. However, these follicles are not yet mature. They are in a kind of dormant state for 12 to 50 years. In this resting stage, germ cell division is halted. The follicles are small and are called primordial follicles. In the fetal and childhood phase, as well as later in fertile adulthood, some of these primordial follicles repeatedly mature into tertiary follicles via primary and secondary follicles due to factors that are not yet understood.

The follicles become larger, but germ cell division is still halted. In this tertiary stage, however, the follicles all die in the fetal and childhood phases because the children do not yet secrete the hormones that the tertiary follicles need for further maturation and germ cell division. This process of death is called atresia.
With the beginning of the pubertyAt puberty, women only have around 400,000 follicles. From this, as in childhood, primordial follicles mature into tertiary follicles. Most of them die, as in childhood. However, 10 to 20 of them manage to mature further in each cycle due to the hormonal influence of the pituitary gland, which takes on its function during puberty.
By gonadotropins (FSH) these selected 10-20 follicles are influenced, one also speaks of a cohort, getting bigger and bigger. One follicle is particularly sensitive to the hormone FSH and is thereby stimulated more than the other follicles in its cohort. This leads to this selected (selected) Follicle becomes the largest of them all. It is known as the dominant follicle. Within a week it grows threefold (approx. 25mm) and has now grown into what is known as a mature follicle. Since this selected follicle is most sensitive to the hormone FSH, there are more intake sites (Receptors) for the hormone, he gets more FSH than the other follicles in the cohort, so to speak. The other follicles are therefore insufficiently influenced and therefore all die (Atresia).

The cohort stimulated by the hormone FSH also always forms hormones, namely estrogens, at the time of further maturation. The dominant follicle produces the largest part of it. These hormones are important as they stimulate the uterus and also the mammary gland. More precisely, this means that the mucous membrane in the uterus is stimulated to grow (proliferate) in order to respond to a possible pregnancy and implantation of the germ to be prepared.

When the mature follicle is very developed, the amount of estrogens produced in the ovaries is so great that the pituitary gland is stimulated to secrete the gonadotropic hormone LH. This LH, in turn, has an effect on the ovaries. The rise in this hormone causes it to ovulate (ovulation) is coming. The mature follicle now continues the germ cell division (the first division is ended and the second division begins). The Egg cell dissolves from the follicle cells and certain enzymes break down the follicle wall and the organ capsule so that the egg cell and the fluid in the follicle find a way towards it Fallopian tubes (tuba uterina) can pave the way. The egg cell is then picked up by the fallopian tube. In the case of a fertilization the egg cell completes its 2nd meiotic division.

The remnants of the follicle, i.e. follicle cells without an egg cell, develop into the so-called after ovulation Corpus luteum (corpus luteum menstruationis). These cells change something and now produce progestin such as, for example progesterone. This hormone has the task of maintaining a possible pregnancy and is formed for this very reason.

The greatest amount of progestin is produced on the 7th day after ovulation. In total, such a corpus luteum lasts 14 days if there is no fertilization. Then the corpus luteum perishes (Luteolysis) and a white scar forms. The corpus luteum is now called Corpus luteum albicans designated. Gestagens are no longer produced, so the pituitary gland is stimulated to release FSH again, so that a new cohort can then be recruited and the cycle starts again from the beginning.

In the case of pregnancy, the corpus luteum persists for two months and, driven by an LH-like hormone (HCG), which is formed by the fertilized germ, further progestins and thus maintains the pregnancy. The corpus luteum, which during the pregnancy is known as the corpus luteum graviditatis.

The ovaries can also cause pain during pregnancy. Information on this topic can be found at Ovarian pain in pregnancy.