Ovarian anatomy

introduction

The ovaries (lat. Ovaries) are among the internal female genital organs. They are created in pairs and lie on either side of the uterus, to which they are connected via the fallopian tubes. The ovaries regulate the woman's menstrual cycle and are essential for a pregnancy to occur.
They also produce the female sex hormones, estrogens and progesterone, which are necessary for the development of the female secondary sexual characteristics.

Ovarian anatomy

The ovaries are created in pairs and lie in small pelvis, in the Ovarian fossa, approximately at the level of the fork of the main artery (Abdominal aorta).
The ovaries are lying intraperitoneallywhich means that the organ is located within the peritoneal cavity (abdominal cavity). The peritoneal cavity is through two sheets of peritoneum educated. The outer leaf, Parietal peritoneum, lines the abdominal cavity from the inside out, while the inner sheet, Visceral peritoneumto the internal organs.
The space between the two leaves is filled with a clear, viscous secretion, which reduces the friction between the organs and thus enables the organs to move safely.

The ovaries are about 3-5 cm long and approx. 1 cm thick. They are oval in shape and are suspended in the abdominal cavity by several elastic, connective tissue bands.
A young ovary has a smooth surface, but after Beginning of sexual maturityin which several follicles (follicle) comes, the ovaries get one blistered, distended surface.

In the immediate vicinity of the ovaries are the Fallopian tubes, the uterus, as well as the ureters and nerves of the lumbar plexus.
The ovaries are supplied with Ovarian arteries (Ovarian arteries), which originate directly from the main artery on both sides, as well as via Branches of the uterine arteries. The venous outflow of blood takes place via the Ovarian veins (Ovarian veins), which enter the renal vein on the left and the inferior vena cava on the right (Inferior vena cava) opens.

The ovaries are innervated by it vegetative nerve plexuses, several of which nerve fibers run directly to the ovaries. From a histological point of view, the ovaries consist of one outer bark and one inner market share.
The cortex contains the egg cells, which are present in follicles and mature with each cycle. In the medulla of the ovaries, which consists of loose connective tissue, there are numerous blood vessels, nerve fibers and lymph vessels.

Position of the ovaries

The ovaries lie in the Ovarian fossa, a small tissue depression in the small basin. It is located approximately at the level where the main artery joins the two pelvic arteries (Aa. Common iliac muscles) divides.
The ovaries lie within the Peritoneum cavity and are adjacent to the ureters and fallopian tubes, as well as to the right Appendix appendix (appendix).

Function of the ovaries

The function of the ovaries is primarily that Production of egg cells. In a newborn girl, there are roughly in both ovaries after birth one to two million egg cells, as Primary follicle (small follicles) are present.
Most of the egg cells perish during a woman's life. Every month one or two follicles mature into a "cracked follicles"Which contains not only the egg cell but also hormone-producing cells.
If he's about 24 millimeters has grown up, he bursts open and the Egg is ejected, in the Fimbria funnel of the fallopian tube and transported to the uterus. The remains in the ovary Rest of the follicular tissue back, from which the Corpus luteum (Corpus luteum) forms.

The corpus luteum lasts about two weeks and above all forms progesterone, which prevents the premature breakdown of the uterine lining. Find one at the time fertilization instead, a Develop pregnancy.
Doesn't find any fertilization instead, the Egg ejected along with the lining of the uterus and it comes to Menstrual period.

Another important function of the ovaries is that Production of female sex hormones (Estrogens and progestins). They are fundamental to that Development of Secondary Sexual Characteristics a woman, as well as for the regulation of the female menstrual cycle and for the Development of pregnancy. Furthermore, the female sex hormones strengthen the bones, have a protective effect on the cardiovascular system and strengthen the immune system.

Female cycle

The sexually mature, fertile phase of life of every woman begins with Menarche and ends with the menopause.
During this time, one follicle matures every month (follicle), with an egg inside, in the ovary. Estrogens and progesterone cause the lining of the uterus to build up and prepare it for the egg cell to implant.

The female cycle consists of two cycles that run in parallel and are interconnected - the mucosal cycle and the ovarian cycle.
The mucosal cycle affects the lining of the uterus and begins on the first day of menstruation. It repeats itself approximately every 28 days if no fertilization has taken place.
The first phase of the mucous membrane cycle is called the "menstrual phase" and includes the first five days of menstruation. If fertilization has not occurred, the corpus luteum is formed (Corpus luteum) and there is a drop in the progesterone concentration in the blood. As a result, the uterine lining is less supplied with blood and is rejected.
During menstruation, about 50-150 milliliters of blood with tissue remnants and mucus are excreted.

Read more about this under Menstruation - the woman's cycle

From day 6 to around ovulation (14th day) one speaks of the "Build-up phase". During this time, more estrogen is released and the uterine lining is rebuilt. The menstrual phase and the build-up phase can vary in time for every woman, so that they can go beyond 14 days.
The last phase is the "Segregation phase“And encloses Day 15-28. After ovulation, in the middle of the cycle, it comes to Formation of the Corpus luteum, which mainly produces progesterone and, in small amounts, also estrogen.
Here comes one further maturation and to one Thickening of the lining of the uterus. Blood vessels grow in - everything is prepared for the egg cell to implant. If fertilization does not take place, the corpus luteum regresses within a few days and hormone production ceases. Then the cycle starts all over again with the menstrual phase.

The Ovarian cycle. He runs in three phases and begins with the "Follicular maturation phase“(Day 1-10). That distributed centrally by the pituitary gland FSH stimulates the ovaries to develop follicles.
The follicle make estrogensthat are released into the blood. During the follicle maturation phase, however, one follicle in particular grows and reaches full maturity, while the other follicles die and are reabsorbed.

From day 11-14 the Ovulation phase. This leads to a sharp increase in the amount distributed centrally LHthat leads to ovulation. The egg cell leaves the ovary and travels via the fallopian tubes towards the uterus. From this day on, the egg cell is Fertile for 24 hours. This is followed by the "Corpus luteum phase“(Day 15-28). The follicle forms in the corpus luteum (Corpus luteum) and begins to produce progesterone and, in small quantities, estrogens. If fertilization does not occur, the corpus luteum regresses and the hormone concentration in the blood drops. Menstruation begins and the cycle begins again.