Uterine Tubes

The uterine tubes, also called the fallopian tubes or oviducts, are paired muscular tubes extending laterally from the superior part of the uterus toward the ovaries. Each tube provides a pathway between the region surrounding an ovary and the uterine cavity.

The uterine tubes are important in reproduction because they receive the ovulated oocyte, provide the usual site of fertilization, support transport of gametes and the early embryo, and convey the developing conceptus toward the uterus. Their anatomy is closely related to the ovaries, broad ligament, uterine vessels, ovarian vessels, and peritoneal cavity.

Location

The uterine tubes lie within the pelvis along the superior free margin of the broad ligament of the uterus. Each extends from the uterine horn laterally toward the corresponding ovary.

The tubes are relatively mobile, particularly in their lateral portions, and their exact position varies with the orientation of the uterus, ovaries, and surrounding pelvic organs.

Length

Each uterine tube is approximately 10 cm long, although individual variation occurs.

The diameter and configuration of the lumen vary substantially along its length, reflecting the different structural and functional characteristics of its four major parts.

Parts of the Uterine Tube

Each uterine tube is divided into four major anatomical regions:

1. Infundibulum
2. Ampulla
3. Isthmus
4. Intramural or uterine part

These regions differ in diameter, wall thickness, mucosal folding, and functional importance.

Infundibulum

The infundibulum is the funnel-shaped lateral end of the uterine tube. It lies close to the ovary and opens into the peritoneal cavity through the abdominal opening of the uterine tube.

The margin of the infundibulum bears multiple finger-like projections called fimbriae.

Fimbriae

The fimbriae are irregular projections extending from the margin of the infundibulum. They lie close to the ovary and assist in directing the ovulated oocyte toward the tubal opening.

The fimbriae are covered by tubal mucosa and participate in movements associated with oocyte capture.

Ovarian Fimbria

One fimbria, the ovarian fimbria, is longer than the others and has a particularly close relationship with the ovary.

It extends toward the tubal pole of the ovary and helps establish an anatomical relationship between the ovary and infundibulum.

Abdominal Opening

The abdominal opening of the uterine tube is located at the center of the infundibulum and communicates directly with the peritoneal cavity.

This communication is anatomically significant because the female reproductive tract provides a potential route between the external environment and the peritoneal cavity through the vagina, uterus, and uterine tubes.

Ampulla

The ampulla is the longest and widest part of the uterine tube. It forms the major portion of the lateral tube and has a relatively thin muscular wall with extensively folded mucosa.

The ampulla is the usual site of fertilization.

Fertilization in the Ampulla

Fertilization most commonly occurs within the ampullary region after sperm have traveled through the uterus and uterine tube and an oocyte has entered from the infundibular end.

The resulting zygote begins early cleavage while being transported toward the uterine cavity.

Isthmus

The isthmus is a short, narrow, relatively straight segment situated medial to the ampulla and close to the uterus.

Its muscular wall is thicker and its lumen narrower than those of the ampulla.

Intramural Part

The intramural part, also called the uterine or interstitial part, passes through the muscular wall of the uterus.

It is the shortest and narrowest portion of the uterine tube and opens into the uterine cavity at the uterine opening.

Uterine Opening

The medial end of each uterine tube communicates with the uterine cavity through the uterine opening.

The two tubal openings are located near the superolateral angles of the uterine cavity.

Comparison of Tubal Regions

Part	Major Feature	Functional Importance
Infundibulum	Funnel-shaped lateral end with fimbriae	Receives the ovulated oocyte
Ampulla	Longest and widest region	Usual site of fertilization
Isthmus	Narrow, thick-walled medial segment	Conducts contents toward uterus
Intramural part	Passes through uterine wall	Connects tube with uterine cavity

Relationship to the Ovary

The lateral end of the uterine tube lies close to the ovary but is not directly attached to the ovarian surface as a continuous closed passage.

When ovulation occurs, the oocyte is released from the ovarian surface into the peritoneal cavity near the infundibulum. The fimbriae and tubal currents assist its movement into the uterine tube.

Relationship to the Uterus

The medial end of each uterine tube enters the uterus near its superolateral angle. The intramural portion traverses the myometrium before opening into the uterine cavity.

The junction between the tube and uterus is important in reproductive physiology and in several clinical procedures involving the uterine cavity and tubal patency.

Relationship to the Broad Ligament

The uterine tubes lie along the superior free margin of the broad ligament. A specialized portion of the broad ligament associated with each tube is called the mesosalpinx.

The broad ligament provides a peritoneal framework through which vessels and nerves can reach the tube.

Mesosalpinx

The mesosalpinx is the portion of the broad ligament associated with and supporting the uterine tube.

It lies inferior to the tube and contains vessels, nerves, and connective tissue associated with the tubal region.

Relationship to the Mesovarium

The mesovarium attaches the ovary to the posterior aspect of the broad ligament, while the mesosalpinx is associated with the uterine tube.

These adjacent peritoneal folds help organize the anatomical relationships among the uterus, uterine tube, and ovary.

Wall of the Uterine Tube

The wall of the uterine tube consists of three principal layers:

• Mucosa
• Muscular layer
• Serosa

The relative thickness and complexity of these layers vary along the length of the tube.

Mucosa

The tubal mucosa forms numerous longitudinal folds that project into the lumen. These folds are especially elaborate in the ampulla and become less complex toward the uterus.

The mucosal surface is lined predominantly by simple columnar epithelium containing ciliated and secretory cells.

Mucosal Folds

The mucosal folds are highly branched in the ampulla, producing a complex luminal architecture. In the narrower isthmus, the folds are generally less elaborate.

The extensive mucosal surface contributes to the specialized environment required for gamete transport and early reproductive events.

Ciliated Cells

Ciliated epithelial cells are prominent within the tubal mucosa. Their cilia generally beat in a direction that assists transport toward the uterus.

Ciliary activity works together with muscular contractions and fluid movement to transport the oocyte and early embryo.

Secretory Cells

Non-ciliated secretory cells within the tubal epithelium produce substances that contribute to the luminal environment.

Tubal secretions support gametes and the early embryo during their passage through the tube.

Tubal Epithelium

Cell Type	Principal Role
Ciliated cells	Contribute to movement of luminal contents toward the uterus
Secretory cells	Contribute fluid and substances supporting the tubal environment

Muscular Layer

The muscular wall of the uterine tube is composed primarily of smooth muscle. Its contractions contribute to transport of sperm, the oocyte, and the early embryo.

The muscular layer becomes relatively more prominent toward the isthmus and uterine end of the tube.

Tubal Peristalsis

Coordinated smooth muscle contractions produce movements commonly described as tubal peristalsis.

These contractions interact with ciliary activity and luminal fluid movement to regulate transport through the uterine tube.

Serosa

Most of the external surface of the uterine tube is covered by serosa, consisting of visceral peritoneum and underlying connective tissue.

This covering is continuous with the peritoneal layers of the broad ligament and mesosalpinx.

Transport of the Oocyte

After ovulation, the oocyte enters the region near the infundibulum. Fimbrial movements, ciliary activity, smooth muscle contractions, and tubal fluid currents contribute to its movement through the tube.

The oocyte does not travel through a direct anatomical connection between the ovary and tube because no such continuous connection exists.

Sperm Transport

Sperm entering the female reproductive tract travel through the cervix and uterine cavity before reaching the uterine tubes.

The tubal environment influences sperm transport and provides the anatomical location where sperm and oocyte normally meet.

Transport of the Early Embryo

After fertilization, the early embryo undergoes cleavage while traveling through the uterine tube toward the uterus.

Normal transport must be coordinated so that the developing conceptus reaches the uterine cavity at an appropriate developmental stage for implantation.

Arterial Supply

The uterine tubes receive arterial blood from branches of both the uterine arteries and ovarian arteries.

These vessels form anastomoses within the mesosalpinx and adjacent portions of the broad ligament.

Tubal Branches of the Uterine Artery

The uterine artery gives off branches that ascend toward the uterine tube from the medial side.

These vessels contribute particularly to the medial portions of the tube and communicate with branches from the ovarian artery.

Tubal Branches of the Ovarian Artery

The ovarian artery gives off tubal branches that approach the uterine tube from the lateral side.

These branches anastomose with branches of the uterine artery, creating a vascular arcade along the tube.

Arterial Supply Overview

Arterial Source	Origin	Contribution
Uterine artery	Internal iliac arterial system	Medial tubal branches
Ovarian artery	Abdominal aorta	Lateral tubal branches

Venous Drainage

Venous drainage generally follows the arterial supply. Tubal veins communicate with both the uterine and ovarian venous networks.

Blood can therefore drain through uterine veins toward the internal iliac system and through ovarian veins toward the abdominal venous system.

Lymphatic Drainage

Lymphatic drainage of the uterine tubes follows pathways associated with both the ovarian and uterine vessels.

The lateral portions tend to drain along ovarian vessels toward lumbar lymph nodes, while more medial portions can drain toward pelvic lymph nodes.

Innervation

The uterine tubes receive autonomic innervation from plexuses associated with the uterus and ovaries.

Sympathetic and parasympathetic fibers participate in regulation of smooth muscle activity and vascular tone.

Autonomic Nerve Supply

Autonomic fibers reach the tube through the ovarian and uterine plexuses. These networks connect with broader abdominal and pelvic autonomic plexuses.

The exact functional effects of autonomic activity interact with hormonal regulation of the reproductive tract.

Embryological Development

The uterine tubes develop from the unfused cranial portions of the paired paramesonephric ducts, also called Müllerian ducts.

The caudal portions of these ducts move medially and fuse to contribute to the uterus and cervix, while the cranial portions remain separate and form the uterine tubes.

Paramesonephric Duct

Each paramesonephric duct begins as an invagination of coelomic epithelium on the lateral aspect of the urogenital ridge.

The cranial end remains open to the coelomic cavity, while the duct elongates caudally alongside the mesonephric duct.

Cranial Müllerian Opening

The open cranial end of the paramesonephric duct contributes to the abdominal opening of the uterine tube.

The surrounding cranial tissue develops into the infundibular and fimbrial region.

Development of the Infundibulum

The cranial portion of the paramesonephric duct expands and becomes the infundibulum of the uterine tube.

Its margins develop into fimbriae positioned near the ovary.

Relationship to Ovarian Development

The uterine tubes and ovaries arise from different embryological structures. The uterine tubes arise from paramesonephric ducts, while the ovaries develop from the gonadal ridges.

The close adult relationship between the ovary and uterine tube is therefore established secondarily during development.

Developmental Origin of Major Structures

Adult Structure	Major Embryological Origin
Ovary	Gonadal ridge with migrating primordial germ cells
Uterine tube	Unfused cranial paramesonephric duct
Uterus	Fused caudal paramesonephric ducts
Cervix	Fused caudal paramesonephric ducts

Congenital Tubal Anomalies

Abnormal formation of the paramesonephric ducts can produce congenital abnormalities of the uterine tubes. These may occur alone or together with abnormalities of the uterus and other Müllerian-derived structures.

The specific anatomy depends on the timing and extent of the developmental disturbance.

Tubal Agenesis

Failure of development of a paramesonephric duct can result in absence or marked underdevelopment of the corresponding uterine tube.

Because Müllerian and urinary development occur in close association, congenital reproductive tract abnormalities can sometimes coexist with renal anomalies.

Ectopic Pregnancy

An ectopic pregnancy occurs when implantation takes place outside the normal endometrial cavity. The uterine tube is the most common location.

Tubal ectopic pregnancy is clinically important because continued growth can distend and eventually rupture the tube, producing potentially severe intraperitoneal hemorrhage.

Ampullary Ectopic Pregnancy

The ampulla is a common site of tubal ectopic implantation. Its relatively wide lumen can initially accommodate an enlarging gestational structure.

Because the ampulla is also the usual site of fertilization, abnormalities of embryo transport can result in implantation before the conceptus reaches the uterus.

Isthmic Ectopic Pregnancy

An ectopic pregnancy can occur within the narrow isthmus. The relatively thick muscular wall and narrow lumen affect the pattern of expansion and potential rupture.

The anatomical location of an ectopic pregnancy influences its imaging appearance and clinical behavior.

Interstitial Pregnancy

An interstitial pregnancy implants within the intramural portion of the uterine tube as it passes through the muscular uterine wall.

This location is surrounded by vascular myometrium and is anatomically distinct from more lateral tubal implantation.

Tubal Blockage

Obstruction of a uterine tube can interfere with passage of sperm, the oocyte, or the early embryo.

Blockage can occur at different levels and may result from congenital abnormalities, inflammation, fibrosis, adhesions, or previous surgery.

Pelvic Inflammatory Disease

Inflammation involving the uterine tubes is called salpingitis. Inflammatory injury can damage the mucosa and produce fibrosis or adhesions.

Alteration of normal tubal anatomy can impair fertility and increase the risk of ectopic implantation.

Hydrosalpinx

A hydrosalpinx is a distended uterine tube containing serous fluid, usually associated with distal tubal obstruction.

The fimbrial end may become sealed, allowing the tube to enlarge as fluid accumulates.

Pyosalpinx

A pyosalpinx is a uterine tube distended with purulent material as a result of infection.

It can occur as part of severe pelvic inflammatory disease and may involve adjacent pelvic structures.

Hemosalpinx

A hemosalpinx refers to accumulation of blood within the uterine tube.

It can occur in association with tubal ectopic pregnancy and other causes of tubal bleeding.

Salpingectomy

Salpingectomy is surgical removal of part or all of a uterine tube. Knowledge of the vascular supply within the mesosalpinx is important during the procedure.

Careful dissection can also be required to preserve adjacent ovarian and uterine structures when appropriate.

Tubal Ligation

Tubal ligation and related sterilization procedures interrupt the continuity of the uterine tubes to prevent sperm and oocyte from meeting.

Different techniques can occlude, divide, remove, or otherwise disrupt portions of the tube.

Hysterosalpingography

Hysterosalpingography is an imaging procedure in which contrast material is introduced through the uterus to evaluate the uterine cavity and patency of the uterine tubes.

When a tube is patent, contrast can pass through the tubal lumen and spill from the abdominal opening into the peritoneal cavity.

Imaging Anatomy

Normal uterine tubes are often difficult to visualize completely on routine imaging because they are narrow and mobile.

They become more conspicuous when distended by fluid, blood, inflammatory material, contrast medium, or pathological processes.

Communication with the Peritoneal Cavity

The uterine tubes are unusual because their lateral openings communicate directly with the peritoneal cavity.

This relationship is important both for normal reproductive function and for understanding potential pathways by which infection or other material can spread between the reproductive tract and peritoneal cavity.

Key Anatomical Relationships

• The uterine tubes extend from the uterus toward the ovaries.
• Each tube is divided into the infundibulum, ampulla, isthmus, and intramural part.
• The infundibulum opens into the peritoneal cavity.
• Fimbriae project from the margin of the infundibulum.
• The ampulla is the longest and widest portion and is the usual site of fertilization.
• The isthmus is narrower and more muscular.
• The intramural portion passes through the uterine wall.
• The uterine tubes lie along the superior margin of the broad ligament.
• The mesosalpinx is the portion of the broad ligament associated with the tube.
• The tubal mucosa contains ciliated and secretory epithelial cells.
• Transport through the tube involves ciliary activity, smooth muscle contractions, and luminal fluid movement.
• Arterial supply comes from both uterine and ovarian arteries.
• The tubes develop from the unfused cranial portions of the paramesonephric ducts.
• The ovary and uterine tube have separate embryological origins.

Clinical Importance

The uterine tubes are clinically important because normal fertility depends on their patency, mucosal integrity, ciliary activity, muscular function, and relationship with the ovaries. Damage or obstruction can interfere with gamete transport and increase the risk of infertility or ectopic pregnancy.

The ampulla is particularly important because it is the usual site of fertilization and a common location for tubal ectopic implantation. The direct communication between the abdominal opening of the tube and the peritoneal cavity also provides a potential route for spread of infection from the reproductive tract into the pelvis.

Understanding the anatomy of the uterine tubes is essential for interpreting hysterosalpingography, evaluating tubal disease, understanding ectopic pregnancy, and performing procedures such as tubal sterilization and salpingectomy.