Corpus: Ovary

The ovary is one of the internal female reproductive organs. Egg cells are formed in the paired ovary, which are expelled monthly during sexual maturity (ovulation). Another important function of the ovary is the production and secretion of female sex hormones.

The gonads (gonads) are located in the genital ridge as indifferent, paired organs on the posterior abdominal wall of the embryo. From the 4th embryonic week, the gonads begin to develop through proliferation. Subsequently, from the 6th embryonic week, the primordial germ cells migrate from the wall of the yolk sac via the dorsal rectal mesentery into the gonadal anlage, where further differentiation of the gonads takes place.

Location[Bearbeiten]

The ovary lies intraperitoneally in the

pelvis (pelvis minor) in a small tissue depression, the ovarian fossa. It is located in the area where the common iliac artery or common iliac vein branches. Due to its oblique position, the laterocranial extremitas tubaria and the mediocaudal extremitas uterina are the poles of the organ. The ligamentum suspensorium ovarii attaches to the extremitas tubaria and connects the ovary to the lateral pelvic wall. The ligamentum ovarii proprium, which connects the ovary to the uterus, attaches to the extremitas uterina.

The obturator nerve and the ureter run dorsal to the ovary.

Shape[Bearbeiten]

The ovary is 3-5 cm long, 0.5-1 cm thick and has an almond-like shape, convex on both sides. The juvenile ovary has a smooth surface. At the onset of sexual maturity, the ovarian surface has vesicular distensions caused by the growth of the ovarian follicles and, particularly in older women, scarred fissures in places where the corpus luteum once formed.

Margo mesovaricus[Bearbeiten]

The forward-facing edge (margo) of the ovary is known as the margo mesovaricus, as this is where the mesovar attaches. The hilum of the ovary is located at the margo mesovaricus.

Margo liber[Bearbeiten]

The free edge of the ovary opposite the margo mesovaricus is called the margo liber. It is directed dorsocaudally.

Vascular pathways[Bearbeiten]

Gefäßversorgung[Bearbeiten]

The vascular supply to the ovary is via the ovarian artery, which arises from the abdominal aorta on both sides caudal to the origin of the renal artery and runs through the ligamentum suspensorium ovarii to the hilum. The ovary receives additional arterial supply from the ramus ovaricus of the uterine artery, which runs laterally to the ovary in the ligamentum ovarii proprium and forms anastomoses with the ovarian artery there.

Venous drainage occurs mainly via the ovarian vein, which flows into the renal vein on the left and directly into the inferior vena cava on the right. If there is also an extensive ovarian venous plexus, there may also be an outflow via the uterine vein.

Nervous supply[Bearbeiten]

The vegetative innervation of the ovary takes place partly via the superior mesenteric plexus and the renal plexus, partly also via the inferior hypogastric plexus, due to the descent (descensus). However, the majority of the fibres run unconnected through the plexuses mentioned. They switch to the 2nd efferent neurone in plexuses close to the organ: Fibres from the renal plexus in the ovarian plexus and fibres from the inferior hypogastric plexus in the uterovaginal plexus. The latter is usually strongly developed and contains numerous ganglion cells as well as fibres. It is therefore also known as the "Frankenhäuser ganglion". As in other organs, the sympathetic fibres mainly innervate the vessels of the ovary and thus regulate the organ's blood supply.

The ovary is surrounded by the single-layered cubic Müller epithelium, which merges into a connective tissue capsule, the tunica albuginea. A layered structure (from outside to inside) can be recognised under the capsule:

• Cortex ovarii, the cortex
• Medulla ovarii, the medulla

The cortex of the ovary contains spinocellular connective tissue, which is only found in the ovary. The medulla contains loose connective tissue.

From a functional point of view, a distinction is made between the ovarian stroma (stroma ovarii) and the ovarian follicles it contains, which represent the parenchyma. The latter are located in the cortex, where follicle maturation takes place. It takes place in the following steps:

• Primordial follicle
• Primary follicle
• Secondary follicle
• Tertiary follicle
• Graaf follicle

The Graafian follicle ruptures during ovulation and releases the mature oocyte into the uterine tube. Follicles contain granulosa cells and theca cells, which surround the oocyte and are synthetically active. In the case of the Graafian follicle, they remain in the ovary after ovulation and transform into the corpus luteum (yellow body). If the egg is not fertilised, the corpus luteum degenerates at the end of the menstrual cycle and remains in the ovary as a connective tissue corpus albicans. If the egg is fertilised, the corpus luteum is preserved for pregnancy through the influence of hormones.

Follicles that do not mature within a menstrual cycle are subject to follicular atresia.

Androgen-producing hilus cells are found in the ovarian medulla.

Diseases of the ovary fall within the specialist area of gynaecology. Important pathologies include:

• Ovarian cysts
• Polycystic ovary (PCO)
• Ovarian tumours
• Ovarian torsion

The ovary is often involved in inflammation of the internal female reproductive organs. In this case, it is referred to as adnexitis. It can also be the site of endometriosis. Malformations of the ovary can be responsible for amenorrhoea

• Image source podcast: © Susan Wilkinson / Unsplash