A fallopian tube looks like a slender, slightly curved tube about 10 centimeters (4 inches) long and roughly 1 centimeter in diameter at its widest point. It flares open at one end into a trumpet-shaped funnel fringed with delicate, finger-like projections. The overall shape resembles a narrow tube that gradually widens as it moves away from the uterus, ending in what looks almost like a small sea anemone reaching toward the ovary.
Overall Shape and Size
Each fallopian tube extends from the upper corner of the uterus outward toward the ovary on the same side. The tube isn’t perfectly straight. It curves gently, and its outer surface is smooth, pale pink, and glistening because it’s draped in a thin membrane that anchors it in place. If you stretched one out, it would be roughly the length of a ballpoint pen, but in the body it sits loosely coiled within the pelvis.
The tube changes dramatically in width from one end to the other. Where it connects to the uterus, the internal opening is a pinpoint: just 0.7 millimeters across, barely wider than the tip of a mechanical pencil lead. By the time you reach the far end near the ovary, the channel opens up to about 1 centimeter, more than ten times wider. This gradual widening gives the tube a subtle funnel shape that’s hard to appreciate from the outside alone.
The Four Distinct Sections
A fallopian tube has four regions, each with a noticeably different look and feel.
The intramural (interstitial) portion is the shortest segment, about 1 centimeter long. You can’t actually see it from the outside because it’s buried within the muscular wall of the uterus. It’s the narrowest part of the entire tube.
The isthmus emerges from the uterus and runs about 3 centimeters. It looks rounded, firm, and cord-like because it has a thick muscular wall relative to its small internal channel, which measures only 1 to 5 millimeters across. If you touched it during surgery, it would feel distinctly firm.
The ampulla is the longest section at about 5 centimeters, and it’s where the tube visibly widens. The wall here is noticeably thinner and softer compared to the isthmus. This is the section where fertilization most often happens. Its inner surface is elaborately folded, though you’d only see that on a cross-section or under magnification.
The infundibulum is the most visually distinctive part. It flares out into a trumpet or funnel shape and is crowned with finger-like projections called fimbriae.
The Fimbriae: Finger-Like Projections
The fimbriae are what make the end of a fallopian tube look so unusual. They’re small, feathery, frond-like projections, each about 1 millimeter wide, attached to the rim of the infundibulum. They extend outward beyond the tube’s muscular wall, giving the opening a fringed or ruffled appearance. One fimbria is noticeably longer than the rest and reaches all the way to the surface of the ovary.
These projections aren’t static. During ovulation, blood vessels inside the fimbriae swell, causing them to puff up and extend closer to the ovary. When ovulation isn’t happening, they relax and sit farther away. Their surfaces are lined with microscopic hair-like structures called cilia that beat rapidly in one direction, creating tiny currents that sweep a released egg into the tube. Think of them as living fingers that actively reach out, catch the egg, and guide it inward.
What It Looks Like Inside
If you sliced a fallopian tube crosswise and looked at it under a microscope, you wouldn’t see a simple hollow channel. The inner lining is thrown into elaborate folds that project inward and fill most of the internal space. In the ampulla, these folds are so extensive and branching that the cross-section looks almost like a complex maze or coral formation. In the isthmus, the folds are simpler and fewer, and the channel is visibly smaller and more circular.
The purpose of all this folding is to ensure that an egg traveling through the tube is always in close contact with the lining. The surface of these folds is covered in two types of cells. Ciliated cells are column-shaped with round nuclei and topped with tiny, rhythmically beating hair-like projections that push the egg toward the uterus. Between them sit narrower secretory cells (sometimes called peg cells) with darker, denser nuclei. These cells produce a nutrient-rich fluid that nourishes both the egg and sperm and helps regulate sperm movement as it swims in the opposite direction toward the ovary.
What an Abnormal Tube Looks Like
Healthy fallopian tubes are so thin that they typically don’t show up on an ultrasound at all. When something is wrong, the change in appearance can be striking. A condition called hydrosalpinx, where fluid gets trapped inside a blocked tube, causes the tube to swell into a shape often described as sausage-like. The delicate, slender tube becomes distended and visibly enlarged, losing its normal tapered profile. The fimbriae at the open end may be fused shut, which is what traps the fluid in the first place.
Surgeons performing laparoscopy can sometimes identify problems by color and texture as well. Scar tissue from infection or endometriosis can make the tube’s surface look dull, thickened, or stuck to surrounding structures rather than hanging freely. A healthy tube, by contrast, appears smooth, mobile, and glistening with a gentle pink hue.
How the Tubes Sit in the Body
The fallopian tubes don’t dangle freely. Each tube is suspended by a thin, fan-shaped fold of tissue called the mesosalpinx, which is part of the broader ligament system that supports the uterus and ovaries. This membrane carries blood vessels and nerves to the tube and gives it enough slack to shift position slightly, which matters during ovulation when the fimbriae need to reach the ovary’s surface. The tubes generally sit in the upper part of the pelvic cavity, curving backward and slightly downward from the top corners of the uterus toward the ovaries on each side.