The fallopian tubes are delicate, muscular channels that are part of the female reproductive system. They serve as the pathway for an egg to travel from the ovary to the uterus. They also provide the environment where an egg can be met by sperm for fertilization.
Physical Characteristics and Location
Each fallopian tube is a thin, J-shaped muscular structure, typically measuring about 10 to 13 centimeters (approximately 4 to 5 inches) in length. These paired tubes are located within the pelvic cavity, extending from the upper sides of the uterus and arching over towards the ovaries, though they are not directly attached.
The tube begins with finger-like projections called fimbriae, located at the end nearest the ovary. These fimbriae surround a funnel-shaped opening, the infundibulum. Extending from the infundibulum is the ampulla, the widest and longest section of the tube.
Following the ampulla, the tube narrows into the isthmus, a muscular and constricted segment that connects directly to the uterus. The inner surface of the fallopian tube is lined with a mucous membrane with many folds and microscopic, hair-like structures called cilia. These cilia move substances through the tube.
The Journey of the Egg
During ovulation, the fimbriae at the end of the fallopian tube become active. They sweep over the ovary, creating currents that help capture the egg. This directs the egg into the infundibulum, the funnel-shaped opening of the tube.
Once inside the fallopian tube, the egg begins its journey towards the uterus. This movement is facilitated by the coordinated beating of cilia lining the tube and wave-like muscular contractions (peristalsis) of the tube’s wall. These actions propel the egg along the tube.
Fertilization by sperm most commonly occurs within the ampulla, the widest part of the fallopian tube. If fertilization occurs, the fertilized egg (zygote) continues its passage. This journey typically takes several days.
Role in Reproductive Health and Complications
Proper fallopian tube function is important for reproductive health. If the tubes become blocked or damaged, they can prevent sperm from reaching the egg or inhibit a fertilized egg from traveling to the uterus, leading to infertility. Conditions such as Pelvic Inflammatory Disease (PID), caused by infections, or endometriosis, where uterine-like tissue grows outside the uterus, can cause scarring and blockages.
An ectopic pregnancy is a significant complication involving the fallopian tube. This occurs when a fertilized egg implants and begins to grow outside the uterus, most frequently in the fallopian tube. The fallopian tube is not designed to expand like the uterus to accommodate a growing pregnancy. This situation requires immediate medical attention due to the risk of rupture and internal bleeding.