fallopian tube, also called oviduct or uterine tube, either of a pair of long narrow ducts located in the human female abdominal cavity that transport the male sperm cells to the egg, provide a suitable environment for fertilization, and transport the egg from the ovary, where it is produced, to the central channel (lumen) of the uterus.
Each fallopian tube is 10–13 cm (4–5 inches) long and 0.5–1.2 cm (0.2–0.6 inch) in diameter. The channel of the tube is lined with a layer of mucous membrane that has many folds and papillae—small cone-shaped projections of tissue. Over the mucous membrane are three layers of muscle tissue; the innermost layer has spirally arranged fibres, the middle layer has circular fibres, and the outermost sheath has longitudinal fibres that end in many fingerlike branches (fimbriae) near the ovaries, forming a funnel-shaped depository called the infundibulum. The infundibulum catches and channels the released eggs; it is the wide distal (outermost) portion of each fallopian tube. The endings of the fimbriae extend over the ovary; they contract close to the ovary’s surface duringovulation in order to guide the free egg. Leading from the infundibulum is the long central portion of the fallopian tube called the ampulla. The isthmus is a small region, only about 2 cm (0.8 inch) long, that connects the ampulla and infundibulum to the uterus. The final region of the fallopian tube, known as the intramural, or uterine, part, is located in the top portion (fundus) of the uterus; it is a narrow tube continuous with the isthmus, and it leads through the thick uterine wall to the uterine cavity, where fertilized eggs normally attach and develop. The channel of the intramural duct is the narrowest part of the fallopian tube.
The mucous membrane lining the fallopian tube gives off secretions that help to transport the sperm and the egg and to keep them alive. The major constituents of the fluid are calcium, sodium, chloride, glucose (a sugar), proteins, bicarbonates, and lactic acid. The bicarbonates and lactic acid are vital to the sperm’s use of oxygen, and they also help the egg to develop once it is fertilized. Glucose is a nutrient for the egg and sperm, whereas the rest of the chemicals provide an appropriate environment for fertilization to occur.
Besides the cells that secrete fluids, the mucous membrane contains cells that have fine hairlike structures called cilia; the cilia help to move the egg and sperm through the fallopian tubes. Sperm deposited in the female reproductive tract usually reach the infundibulum within a few hours. The egg, whether fertilized or not, takes three to four days to reach the uterine cavity. The swaying motions of the cilia and the rhythmic muscular contractions (peristaltic waves) of the fallopian tube’s wall work together while moving the egg or sperm.
What Are the Signs & Symptoms of Blocked Fallopian Tubes?
Millions of women suffer from blocked fallopian tubes, and the condition is one of the most common causes of infertility. Fallopian tubes can be blocked because of scarring caused by injury or infection, but the underlying cause of the condition is sometimes unknown. Although common, blocked fallopian tubes are rarely a cause for serious concern. Because blocked fallopian tubes are often asymptomatic or present only with very mild symptoms, the condition is underdiagnosed, however it is a leading cause of infertility.
Infertility Caused by a Blocked Fallopian Tube.
Women who are not trying to conceive may be completely unaware of their blocked fallopian tubes, since infertility is often the only symptom. Since a blockage in the fallopian tubes can prevent sperm and eggs from traveling freely, they may be unable to join and create a zygote.Women with one occluded fallopian tube may have difficulty conceiving, but if the other tube is fully functional, the patient may never experience noticeable infertility. However, women with two affected fallopian tubes may find it nearly impossible to conceive without treatment or in vitro fertilization.