distal ostia of the Fallopian tubes
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The fallopian tubes, also known as uterine tubes, oviducts or salpinges (singular salpinx), are paired tubes in the human female that stretch from the uterus to the ovaries. The fallopian tubes are part of the female reproductive system. In other mammals they are only called oviducts. Each tube is a muscular
hollow organ In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a ...
that is on average between 10 and 14 cm in length, with an external diameter of 1 cm. It has four described parts: the intramural part, isthmus, ampulla, and infundibulum with associated fimbriae. Each tube has two openings a proximal opening nearest and opening to the uterus, and a distal opening furthest and opening to the abdomen. The fallopian tubes are held in place by the
mesosalpinx The mesosalpinx is part of the lining of the abdominal cavity in higher vertebrates, specifically the portion of the broad ligament that stretches from the ovary to the level of the fallopian tube. See also * Mesometrium * Mesovarium * Salpinx i ...
, a part of the broad ligament
mesentery The mesentery is an organ that attaches the intestines to the posterior abdominal wall in humans and is formed by the double fold of peritoneum. It helps in storing fat and allowing blood vessels, lymphatics, and nerves to supply the intestines ...
that wraps around the tubes. Another part of the broad ligament, the mesovarium suspends the ovaries in place. An
egg cell The egg cell, or ovum (plural ova), is the female reproductive cell, or gamete, in most anisogamous organisms (organisms that reproduce sexually with a larger, female gamete and a smaller, male one). The term is used when the female gamete is ...
is transported from an ovary to a fallopian tube where it may be fertilized in the ampulla of the tube. The fallopian tubes are lined with
simple columnar epithelium Simple columnar epithelium is a single layer of columnar epithelial cells which are tall and slender with oval-shaped nuclei located in the basal region, attached to the basement membrane. In humans, simple columnar epithelium lines most organ ...
with hairlike extensions called
cilia The cilium, plural cilia (), is a membrane-bound organelle found on most types of eukaryotic cell, and certain microorganisms known as ciliates. Cilia are absent in bacteria and archaea. The cilium has the shape of a slender threadlike projecti ...
which together with
peristaltic Peristalsis ( , ) is a radially symmetrical contraction and relaxation of muscles that propagate in a wave down a tube, in an anterograde direction. Peristalsis is progression of coordinated contraction of involuntary circular muscles, which ...
contractions from the muscular layer, move the fertilized egg (zygote) along the tube. On its journey to the uterus the zygote undergoes cell divisions that changes it to a
blastocyst The blastocyst is a structure formed in the early embryonic development of mammals. It possesses an inner cell mass (ICM) also known as the ''embryoblast'' which subsequently forms the embryo, and an outer layer of trophoblast cells called the t ...
an early embryo, in readiness for implantation. Almost a third of cases of
infertility Infertility is the inability of a person, animal or plant to reproduce by natural means. It is usually not the natural state of a healthy adult, except notably among certain eusocial species (mostly haplodiploid insects). It is the normal state ...
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. The name comes from the Italian Catholic priest and anatomist Gabriele Falloppio, for whom other anatomical structures are also named.


Structure

Each fallopian tube leaves the uterus at an opening at the uterine horns known as the proximal tubal opening or ''proximal ostium''. The tubes have an average length of that includes the intramural part of the tube. The tubes extend to near the ovaries where they open into the abdomen at the distal tubal openings. In other
mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
s the fallopian tube is called the oviduct which may also be used in reference to the fallopian tube in the human. The fallopian tubes are held in place by the
mesosalpinx The mesosalpinx is part of the lining of the abdominal cavity in higher vertebrates, specifically the portion of the broad ligament that stretches from the ovary to the level of the fallopian tube. See also * Mesometrium * Mesovarium * Salpinx i ...
a part of the broad ligament
mesentery The mesentery is an organ that attaches the intestines to the posterior abdominal wall in humans and is formed by the double fold of peritoneum. It helps in storing fat and allowing blood vessels, lymphatics, and nerves to supply the intestines ...
that wraps around the tubes. Another part of the broad ligament, the mesovarium suspends the ovaries in place.


Parts

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.


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.


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. The isthmus contains a large number of secretory cells.


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. The ampulla contains a large number of ciliated epithelial cells. It is thin walled with a much folded luminal surface, and opens into the infundibulum.


Infundibulum

The infundibulum opens into the abdomen at the distal tubal opening and rests above the ovary. Most cells here are ciliated epithelial cells. The opening is surrounded by fimbriae, which help in the collection of the oocyte after ovulation. 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. They are attached to the ends of the infundibulum, extending from its inner circumference, and muscular wall. The cilia beat towards the fallopian tube. 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. 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. An ovary is not directly connected to its adjacent fallopian tube. When ovulation is about to occur, the sex hormones activate the fimbriae, causing them to swell with blood, extend, and hit the ovary in a gentle, sweeping motion. An oocyte is released from the ovary into the peritoneal cavity and the cilia of the fimbriae sweep it into the fallopian tube.


Microanatomy

When viewed under the microscope, the fallopian tube has three layers. From outer to inner, these are the serosa,
muscularis mucosae The lamina muscularis mucosae (or muscularis mucosae) is a thin layer (lamina) of muscle of the gastrointestinal tract, located outside the lamina propria, and separating it from the submucosa. It is present in a continuous fashion from the esopha ...
, and the
mucosa A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It is ...
. The outermost covering layer of serous membrane is known as the serosa. The serosa is derived from the visceral peritoneum. The muscularis mucosae consists of an outer ring of
smooth muscle Smooth muscle is an involuntary non-striated muscle, so-called because it has no sarcomeres and therefore no striations (''bands'' or ''stripes''). It is divided into two subgroups, single-unit and multiunit smooth muscle. Within single-unit mus ...
arranged longitudinally, and a thick inner circular ring of smooth muscle. This layer is responsible for the rhythmic
peristaltic Peristalsis ( , ) is a radially symmetrical contraction and relaxation of muscles that propagate in a wave down a tube, in an anterograde direction. Peristalsis is progression of coordinated contraction of involuntary circular muscles, which ...
contractions of the fallopian tubes, that with the cilia move the egg cell towards the uterus. The innermost mucosa is made up of a layer of luminal epithelium, and an underlying thin layer of loose connective tissue the
lamina propria The lamina propria is a thin layer of connective tissue that forms part of the moist linings known as mucous membranes or mucosae, which line various tubes in the body, such as the respiratory tract, the gastrointestinal tract, and the urogenita ...
. There are three different cell types in the epithelium. Around 25% of the cells are ciliated columnar cells; around 60% are secretory cells, and the rest are
peg cell A peg cell is a non-ciliated epithelial secretory cell within the uterine tube (oviduct or Fallopian tube). These cells represent one of three epithelial cell types found within the normal fallopian tube epithelium and only make up around 10% of the ...
s thought to be a secretory cell variant. The ciliated cells are most numerous in the infundibulum, and the ampulla. Estrogen increases the formation of cilia on these cells. Peg cells are shorter, have surface
microvilli Microvilli (singular: microvillus) are microscopic cellular membrane protrusions that increase the surface area for diffusion and minimize any increase in volume, and are involved in a wide variety of functions, including absorption, secretion, ...
, and are located between the other epithelial cells. The presence of immune cells in the mucosa has also been reported with the main type being CD8+ T-cells. Other cells found are B lymphocytes,
macrophage Macrophages (abbreviated as M φ, MΦ or MP) ( el, large eaters, from Greek ''μακρός'' (') = large, ''φαγεῖν'' (') = to eat) are a type of white blood cell of the immune system that engulfs and digests pathogens, such as cancer cel ...
s, NK cells, and
dendritic cell Dendritic cells (DCs) are antigen-presenting cells (also known as ''accessory cells'') of the mammalian immune system. Their main function is to process antigen material and present it on the cell surface to the T cells of the immune system. ...
s. 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.


Development

Embryo An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...
s develop a genital ridge that forms at their tail end and eventually forms the basis for the urinary system and reproductive tracts. Either side and to the front of this tract, around the sixth week develops a duct called the
paramesonephric duct Paramesonephric ducts (or Müllerian ducts) are paired ducts of the embryo that run down the lateral sides of the genital ridge and terminate at the sinus tubercle in the primitive urogenital sinus. In the female, they will develop to form the fal ...
, also called the Müllerian duct. A second duct, the mesonephric duct, develops adjacent to this. Both ducts become longer over the next two weeks, and the paramesonephric ducts around the eighth week cross to meet in the midline and fuse. One duct then regresses, with this depending on whether the embryo is genetically female or male. In females, the paramesonephric duct remains, and eventually forms the female reproductive tract. The portions of the paramesonephric duct which are more
cranial Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...
—that is, further from the tail-end, end up forming the fallopian tubes. In males, because of the presence of the Y sex chromosome, anti-Müllerian hormone is produced. This leads to the degeneration of the paramesonephric duct. 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. 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 Paired box gene 2, also known as Pax-2, is a protein which in humans is encoded by the ''PAX2'' gene. Function The Pax Genes, or Paired-Box Containing Genes, play important roles in the development and proliferation of multiple cell lines, dev ...
, and
Emx2 Homeobox protein Emx2 is a protein that in humans is encoded by the ''EMX2'' gene. Function The homeodomain transcription factor EMX2 is critical for central nervous system and urogenital development. EMX1 (MIM 600034) and EMX2 are related to t ...
.
Embryo An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...
s have two pairs of ducts that will let gametes out of the body when they are adults; one pair (the Müllerian ducts) develops in females into the fallopian tubes, uterus, and vagina, while the other pair (the
Wolffian duct The mesonephric duct (also known as the Wolffian duct, archinephric duct, Leydig's duct or nephric duct) is a paired organ that forms during the embryonic development of humans and other mammals and gives rise to male reproductive organs. Stru ...
s) develops in males into the
epididymis The epididymis (; plural: epididymides or ) is a tube that connects a testicle to a vas deferens in the male reproductive system. It is a single, narrow, tightly-coiled tube in adult humans, in length. It serves as an interconnection between the ...
and vas deferens. The homologous organ in the male is the
appendix testis The appendix testis (or hydatid of Morgagni) is a vestigial remnant of the Müllerian duct, present on the upper pole of the testis and attached to the tunica vaginalis. It is present about 90% of the time. Clinical significance Torsion The appen ...
.


Function


Fertilization

The fallopian tube allows the passage of an egg from the ovary to the uterus. When an oocyte is developing in an ovary, it is surrounded by a spherical collection of cells known as an ovarian follicle. Just before ovulation, the primary oocyte completes meiosis I to form the first polar body and a secondary oocyte which is arrested in metaphase of meiosis II. At the time of ovulation in the
menstrual cycle The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that make pregnancy possible. The ovarian cycle controls the production and release of eggs a ...
, the secondary oocyte is released from the ovary. The follicle and the ovary's wall rupture, allowing the secondary oocyte to escape. The secondary oocyte is caught by the fimbriated end of the fallopian tube and travels to the ampulla. Here, the egg is able to become fertilized with sperm. The ampulla is typically where the sperm are met and fertilization occurs; meiosis II is promptly completed. After fertilization, the ovum is now called a zygote and travels toward the uterus with the aid of the hairlike
cilia The cilium, plural cilia (), is a membrane-bound organelle found on most types of eukaryotic cell, and certain microorganisms known as ciliates. Cilia are absent in bacteria and archaea. The cilium has the shape of a slender threadlike projecti ...
and the activity of the muscle of the fallopian tube. The early embryo requires critical development in the fallopian tube. After about five days, the new
embryo An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...
enters the uterine cavity and, on about the sixth day, begins to
implant Implant can refer to: Medicine *Implant (medicine), or specifically: ** Brain implant ** Breast implant **Buttock implant **Cochlear implant **Contraceptive implant **Dental implant ** Fetal tissue implant **Implantable cardioverter-defibrillator ...
on the wall of the uterus. 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.


Clinical significance

Almost a third of cases of
infertility Infertility is the inability of a person, animal or plant to reproduce by natural means. It is usually not the natural state of a healthy adult, except notably among certain eusocial species (mostly haplodiploid insects). It is the normal state ...
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 infection Sexually transmitted infections (STIs), also referred to as sexually transmitted diseases (STDs) and the older term venereal diseases, are infections that are Transmission (medicine), spread by Human sexual activity, sexual activity, especi ...
s can lead to infertility.


Inflammation

Salpingitis Salpingitis is an infection causing inflammation in the Fallopian tubes (also called ''salpinges''). It is often included in the umbrella term of pelvic inflammatory disease (PID), along with endometritis, oophoritis, myometritis, parametritis, ...
is inflammation of the fallopian tubes and may be found alone, or with other
pelvic inflammatory disease Pelvic inflammatory disease, also known as pelvic inflammatory disorder (PID), is an infection of the upper part of the female reproductive system, namely the uterus, fallopian tubes, and ovaries, and inside of the pelvis. Often, there may be no ...
s (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 Endometriosis is a disease of the female reproductive system in which cells similar to those in the endometrium, the layer of tissue that normally covers the inside of the uterus, grow outside the uterus. Most often this is on the ovaries, f ...
, it may lead to
fallopian tube obstruction Fallopian tube obstruction, also known as fallopian tube occlusion is a major cause of female infertility. Blocked fallopian tubes are unable to let the ovum and the sperm converge, thus making fertilization impossible. Fallopian tubes are also kno ...
. Fallopian tube obstruction may be a cause of
infertility Infertility is the inability of a person, animal or plant to reproduce by natural means. It is usually not the natural state of a healthy adult, except notably among certain eusocial species (mostly haplodiploid insects). It is the normal state ...
or
ectopic pregnancy Ectopic pregnancy is a complication of pregnancy in which the embryo attaches outside the uterus. Signs and symptoms classically include abdominal pain and vaginal bleeding, but fewer than 50 percent of affected women have both of these symptoms. ...
.


Blockage or narrowing

If a blocked fallopian tube has affected fertility, its repair where possible may increase the chances of becoming pregnant. Tubal obstruction can be proximal, distal or mid-segmental.Tubal obstruction is a major cause of infertility but full testing of tubal functions is not possible. However, the testing of patency – whether or not the tubes are open can be carried out using hysterosalpingography, laparoscopy and dye, or hystero contrast sonography (HyCoSy). During surgery, the condition of the tubes may be inspected and a dye such as
methylene blue Methylthioninium chloride, commonly called methylene blue, is a salt used as a dye and as a medication. Methylene blue is a thiazine dye. As a medication, it is mainly used to treat methemoglobinemia by converting the ferric iron in hemoglobin ...
can be injected into the uterus and shown to pass through the tubes when the
cervix The cervix or cervix uteri (Latin, 'neck of the uterus') is the lower part of the uterus (womb) in the human female reproductive system. The cervix is usually 2 to 3 cm long (~1 inch) and roughly cylindrical in shape, which changes during ...
is occluded. As tubal disease is often related to ''Chlamydia'' infection, testing for ''Chlamydia'' antibodies has become a cost-effective screening device for tubal pathology.


Ectopic pregnancy

Occasionally the embryo
implants Implant can refer to: Medicine *Implant (medicine), or specifically: **Brain implant **Breast implant **Buttock implant **Cochlear implant **Contraceptive implant **Dental implant **Fetal tissue implant **Implantable cardioverter-defibrillator ** ...
outside of the uterus, creating an
ectopic pregnancy Ectopic pregnancy is a complication of pregnancy in which the embryo attaches outside the uterus. Signs and symptoms classically include abdominal pain and vaginal bleeding, but fewer than 50 percent of affected women have both of these symptoms. ...
. Most ectopic pregnancies occur in the fallopian tube, and are commonly known as ''tubal pregnancies''.


Surgery

The surgical removal of a fallopian tube is called a
salpingectomy Salpingectomy refers to the surgical removal of a Fallopian tube. This may be done to treat an ectopic pregnancy or cancer, to prevent cancer, or as a form of contraception. This procedure is now sometimes preferred over its ovarian tube-sparin ...
. 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 Tuboplasty refers to a number of surgical operations that attempt to restore patency and functioning of the fallopian tube(s) so that a pregnancy could be achieved. As tubal infertility is a common cause of infertility, tuboplasties were commonly ...
. A surgical procedure to permanently prevent conception is tubal ligation.


Cancer

Fallopian tube cancer Primary fallopian tube cancer (PFTC), often just tubal cancer, is a malignant neoplasm that originates from the fallopian tube. Signs and symptoms The internal location of the fallopian tubes makes it difficult to reach an early diagnosis. Sympto ...
, which typically arises from the epithelial lining of the fallopian tube, has historically been considered to be a very rare malignancy. Evidence suggests it probably represents a significant portion of what has previously been classified as ovarian cancer, as much as 80 per cent. These are classed as serous carcinomas, and are usually located in the fimbriated distal tube.


Other

In rare cases a fallopian tube may prolapse into the vaginal canal following a
hysterectomy Hysterectomy is the surgical removal of the uterus. It may also involve removal of the cervix, ovaries (oophorectomy), Fallopian tubes (salpingectomy), and other surrounding structures. Usually performed by a gynecologist, a hysterectomy may b ...
. The swollen fimbriae can have the appearance of an
adenocarcinoma Adenocarcinoma (; plural adenocarcinomas or adenocarcinomata ) (AC) is a type of cancerous tumor that can occur in several parts of the body. It is defined as neoplasia of epithelial tissue that has glandular origin, glandular characteristics, or ...
.


History

The fallopian tube was first described as a structure linked to fertilization by the Greek physician Soranus of Ephesus (
1st century The 1st century was the century spanning AD 1 ( I) through AD 100 ( C) according to the Julian calendar. It is often written as the or to distinguish it from the 1st century BC (or BCE) which preceded it. The 1st century is considered part o ...
AD). The fallopian tubes were named by Vesalius after his assistant the 16th-century Italian anatomist Gabriele Falloppio, the first person to provide a detailed description of the tubes. He thought they resembled trumpets, ' in Italian, which was misunderstood and became the English "tube". Though the name ''Fallopian tube'' is eponymous, it is often spelt with a lower case ''f'' from the assumption that the adjective ''fallopian'' has been absorbed into modern English as the ' name for the structure.
Merriam-Webster Merriam-Webster, Inc. is an American company that publishes reference books and is especially known for its dictionaries. It is the oldest dictionary publisher in the United States. In 1831, George and Charles Merriam founded the company as ...
dictionary for example lists ''fallopian tube'', often spelt ''Fallopian tube''.


Additional images

File:Illu ovary.jpg, Image showing numbered parts of the fallopian tubes and surrounding structures File:Scheme female reproductive system-number-full-cropped.svg, Female reproductive system numbered parts File:Gray1161.png, Image showing the right fallopian tube (here labeled the uterine tube) seen from behind. The uterus, ovaries and right broad ligament are labeled. File:Normal Fallopian Tube, Human.jpg, Cross-section of fallopian tube,
stained A stain is a discoloration that can be clearly distinguished from the surface, material, or medium it is found upon. They are caused by the chemical or physical interaction of two dissimilar materials. Accidental staining may make materials app ...
and viewed under microscope


References


External links


Histology image: 18501loa
– Histology Learning System at Boston University

{{DEFAULTSORT:Fallopian Tube Pelvis Human female reproductive system