Uterus

The uterus, also called the womb, is the organ of pregnancy and the largest of the organs of the female reproductive system of most mammals. It is a muscular, hollow, pear-shaped, intraperitoneal organ, located in the lesser pelvis of the woman that, when she assumes the anteverted position, rests on the urinary bladder in front, with the rectum behind her. It houses the blastula, which is implanted in the endometrium, beginning gestation, which in the human species lasts around 280 days.

Function

The main function of the uterus is to receive the zygote for its implantation and nutrition, through blood vessels specially developed for that purpose. The fertilized egg then becomes an embryo that develops into a fetus, to later be born a young of the given species.

Morphologies in mammals

Among different species of mammals, the uterus can be observed to take one of four basic forms:

• Bipartite: Typical in pigs, cats and dogs.
• Bicorne: Especially among ruminants (wine, goat, sheep, camels, giraffes, bison, buffaloes, veins, etc.).
• Simple: Found in humans and other primates
• Double: Characteristic of rodents (ratons, rats and hamsters), marsupials and lakemorpha (rabbits and hares).

Anatomy of the uterus in women

Flat of the woman's pelvis. Anatomical relationships between bladder, uterus, rectum and sacral are seen. Semi-schematic drawing (year 1858).

The uterus consists of a body, a base or bottom (isthmus), a neck or cervix, and a mouth. It is suspended in the pelvis and is positioned with the base pointing up and forward, and the neck pointing slightly back. It is connected to the vagina through the cervix; on each of its sides is an ovary that produces ova or eggs that reach it through the fallopian tubes. When there is no pregnancy, the uterus is about 7.6 cm long, 5 cm wide. Although the uterus is a muscular organ, it has a lining of soft glandular material that thickens during ovulation, at which point it is ready to receive a fertilized egg. If fertilization does not occur, this lining is shed during menstruation.

Regions

The uterus is made up of two distinct areas in shape and function, which are:

• The uterine bodyto which the uterine tubes are attached. It is separated from the cervix or cervix by the uterine isthmus.
• The neck or cervix uterine it communicates with the isthmus at its upper end, while the lower end ends by making it slide forward in the upper portion of the vagina, which comes to be called portio or "twisting hocico". The external cervical orifice through which the cervix flows into the vagina, acquires different form according to parity, an event that can be visualized by colposcopy, or direct cervical examination.

Layers

Human only. Cut showing cervix, body and fallopian tube. Semi-schematic drawing.

The uterus is partially covered by peritoneum in the uterine fundus, in its uppermost and posterior portion. On the sides it presents the round ligaments and in front the bladder.

The wall of the uterus presents to the section three layers of cells that are from outside to inside:

• Serosa or perimeter, corresponds to the peritoneum in the posterosuperior part, and the lax tissue that spreads on the sides of the uterus in what is called parameters.
• Miometrium, formed mainly by smooth muscle tissue. The innermost layer of myometrium is a transition zone that thickens in adenomiosis.
• Endometrial is a layer of specialized epithelium, called mucosa, which is renewed in every menstrual cycle of non-fertilization. It is the portion poured during menstruation or period throughout the fertile years of the woman. In other mammals the menstrual cycle may be separated from each other for several days and up to six months.

Support

The uterus is supported primarily by the pelvic diaphragm. Secondarily, it receives support from ligaments and the peritoneum through the broad ligament of the uterus.

The uterus is held in its position by several peritoneal ligaments, there are several but the most important are two, one for each side of the uterus:

Other ligaments near the uterus, such as:

• Wide League
• Round league
• Ovary's own league
• Infundibulopélvico or suspensory ligament of the ovary

They have little role in supporting the uterus.

Irrigation and lymphatic drainage

The uterus is supplied by the uterine arteries, branches of the hypogastric artery, and innervated by the superior and inferior hypogastric plexuses. It is also supplied by branches from the ovarian arteries, branches of the aortic artery.

Lymphatic drainage is directed primarily to the internal and external iliac lymph nodes, toward the para-aortic lymph nodes.

Pathologies

The anterior face of the uterus while sutured followed by a Caesarean.

The uterus is prone to infection. Endometritis is an inflammation of the mucous lining of the uterus that can affect both the cervix and the body of the organ, or both. Cancer and fibrous tumors of the uterus are quite common, as is endometriosis, which consists of the appearance of the uterine lining outside the female organ. Adenomyosis is the nesting of the endometrium in the muscular layer of the uterus, the myometrium.

As the organ of menstruation, the uterus is prone to disturbances that cause dysfunctional uterine bleeding and endometrial hyperplasia.

Leiomyoma, commonly known as uterine myomatosis, is the thickening of the uterine body, generally organized, forming tumors, which are 80% benign. altering its anatomy and sometimes causes dysfunctional bleeding or bleeding that does not correspond to the menstrual period, a pathology that women present after 40 years of age, very rare in young women.

Endometrial cancer occurs more frequently in women older than 55 years and tends to be strongly associated with obesity, diabetes and hypertension.

Removal of the uterus is called a hysterectomy.

Uterus transplant

First performed in 2014 on humans, both live and cadaveric uteruses have been used. Few pregnancies have come to term after transplantation.

Artificial uterus

Human pregnancy lasts an average of 40 weeks. Advances in neonatal intensive care have managed to push the limits of viability to 22-23 weeks of gestation, although with great disabilities and a reduced quality of life. The artificial uterus will be a device that will preserve life outside the body (ectogenesis) of premature infants between 23 weeks and up to 28 weeks, the period that puts their survival at risk. The artificial uterus is in the experimental phase, it has only been tested in premature sheep. The researchers had to solve two problems that prevent the use of conventional incubators in such immature living beings. On the one hand, extremely premature babies have underdeveloped hearts and cannot withstand the pressure of an external blood circulation system. In the artificial uterus, the circulation of blood, which reaches it through a synthetic umbilical cord, is the fetus with its own heart, which circulates the blood and thus acquires the nutrients it needs. On the other hand, since its lungs are not yet functional enough to breathe in an oxygen atmosphere, the premature animal is immersed in an amniotic fluid with which it exchanges oxygen and carbon dioxide through the lungs.
The entire system maintains constant temperature, pressure and light in an environment that completely simulates the interior of a placenta. The animals have been kept alive and in perfect health conditions for 28 days (4 weeks). This technique will not be applicable in the short term.