Fallopian tube

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The fallopian tubes, also known as uterine tubes, oviducts^[1] or salpinges (sg.: salpinx), are paired tubes in the human female body that stretch from the uterus to the ovaries. The fallopian tubes are part of the female reproductive system. In other vertebrates, they are only called oviducts.^[2]

Each tube is a muscular

Almost a third of cases of infertility are caused by fallopian tube pathologies. These include inflammation, and tubal obstructions. A number of tubal pathologies cause damage to the cilia of the tube, which can impede movement of the sperm or egg.^[7]

The name comes from the

Each tube is composed of four parts: from inside the proximal tubal opening the intramural or interstitial part, that links to the narrow isthmus, the isthmus connects to the larger ampulla, which connects with the infundibulum and its associated fimbriae that opens into the peritoneal cavity from the distal tubal opening.^[12]

Intramural part

The intramural part or interstitial part of the fallopian tube lies in the myometrium, the muscular wall of the uterus. This is the narrowest part of the tube that crosses the uterus wall to connect with the isthmus. The intramural part is 0.7 mm wide and 1 cm long.^[12]

Isthmus

The narrow isthmus links the tube to the uterus, and connects to the ampulla. The isthmus is a rounded, and firm muscular part of the tube. The isthmus is 1–5 mm wide, and 3 cm long.^[12] The isthmus contains a large number of secretory cells.^[10]

Ampulla

The ampulla is the major part of the fallopian tube. The ampulla is the widest part of the tube with a maximal luminal diameter of 1 cm, and a length of 5 cm. It curves over the ovary, and is the primary site of fertilization.^[12] The ampulla contains a large number of ciliated epithelial cells.^[10] It is thin walled with a much folded luminal surface, and opens into the infundibulum.^[12]

Infundibulum

The infundibulum opens into the abdomen at the distal tubal opening and rests above the ovary. Most cells here are ciliated epithelial cells.^[10] The opening is surrounded by fimbriae, which help in the collection of the oocyte after ovulation.^[4] The fimbriae (singular fimbria) is a fringe of densely ciliated tissue projections of approximately 1 mm in width around the distal tubal opening, oriented towards the ovary.^[12] They are attached to the ends of the infundibulum, extending from its inner circumference, and muscular wall.^[12] The cilia beat towards the fallopian tube.^[12] Of all the fimbriae, one fimbria known as the ovarian fimbria is long enough to reach and make contact with the near part of the ovary during ovulation.^[13][14][12] The fimbriae have a higher density of blood vessels than the other parts of the tube, and the ovarian fimbria is seen to have an even higher density.^[8]

An ovary is not directly connected to its adjacent fallopian tube. When ovulation is about to occur, the

Microanatomy

When

The outermost covering layer of serous membrane is known as the serosa.^[6] The serosa is derived from the visceral peritoneum.^[14]

The muscularis mucosae consists of an outer ring of

The histological features of tube vary along its length. The mucosa of the ampulla contains an extensive array of complex folds, whereas the relatively narrow isthmus has a thick muscular coat and simple mucosal folds.[14]

Development

As the uterus develops, the part of the fallopian tubes closer to the uterus, the ampulla, becomes larger. Extensions from the fallopian tubes, the fimbriae, develop over time. Cell markers have been identified in the fimbriae, which suggests that their embryonic origin is different from that of the other tube segments.[8]

Apart from the presence of sex chromosomes, specific genes associated with the development of the fallopian tubes include the Wnt and Hox groups of genes, Lim1, Pax2, and Emx2.^[17]

The fallopian tube allows the passage of an egg from the ovary to the uterus. When an

At the time of

The release of an oocyte does not alternate between the two ovaries and seems to be random. After removal of an ovary, the remaining one produces an egg every month.^[18]

Clinical significance

Almost a third of cases of infertility are caused by fallopian tube pathologies. These include inflammation, and tubal obstructions. A number of tubal pathologies cause damage to the cilia of the tube, which can impede movement of the sperm or egg. A number of sexually transmitted infections can lead to infertility.^[7]

Inflammation

Salpingitis is inflammation of the fallopian tubes and may be found alone, or with other pelvic inflammatory diseases (PIDs). A thickening of the fallopian tube at its narrow isthmus portion, due to inflammation, is known as salpingitis isthmica nodosa. Like another PID endometriosis, it may lead to fallopian tube obstruction. Fallopian tube obstruction may be a cause of infertility or ectopic pregnancy.^[19]

Blockage or narrowing

If a

Occasionally the embryo implants outside of the uterus, creating an ectopic pregnancy. Most ectopic pregnancies occur in the fallopian tube, and are commonly known as tubal pregnancies.^[22]

Surgery

The surgical removal of a fallopian tube is called a salpingectomy. To remove both tubes is a bilateral salpingectomy. An operation that combines the removal of a fallopian tube with the removal of at least one ovary is a salpingo-oophorectomy. An operation to remove a fallopian tube obstruction is called a tuboplasty. A surgical procedure to permanently prevent conception is tubal ligation.

Cancer

In rare cases, a fallopian tube may prolapse into the vaginal canal following a hysterectomy. The swollen fimbriae can have the appearance of an adenocarcinoma.^[24]

History

The Greek doctor Herophilus, in his treatise on midwifery, points out the existence of the two ducts that he supposed transported "female semen". Then Galen, already in the modern era, described that the paired ducts indicated by Herophilus were connected to the uterus.

In 1561, the Renaissance doctor Gabriele Falloppio published his book Observationes Anatomicae. Its contribution is a detailed description of the "tubal" of the uterus and its different portions, with its farthest (distal) end open towards the abdomen, and the other (proximal) connected to the uterus.^[25][26]

Though the name Fallopian tube is

• 
  Image showing numbered parts of the fallopian tubes and surrounding structures
• 
  Female reproductive system numbered parts
• 
  Image showing the right fallopian tube (here labeled the uterine tube) seen from behind. The uterus, ovaries and right broad ligament are labeled.
• 
  Cross-section of fallopian tube, stained and viewed under microscope

References

This article incorporates text in the public domain from page 1257 of the 20th edition of Gray's Anatomy (1918)

External links

Wikimedia Commons has media related to Fallopian tube.

• Histology image: 18501loa – Histology Learning System at Boston University
• Menstrual Cycle - Merck