In this video, we're going to be talking about the uterine tubes, also known as the fallopian tubes. So the uterine tubes are the initial or first part of the female duct system and they are going to be the structure that receives the ovulated oocyte and each uterine tube has 3 regions. So the first region is called the infundibulum and the infundibulum is the opening of the uterine tube into the peritoneal cavity. And infundibulum is a term used pretty commonly in anatomy and it's usually used to indicate that something has like a funnel like shape or a funnel like structure. So I always think of how infundibulum has the word fun in it just like funnel does and that kind of helps me remember that.

Now the margin of the infundibulum or the end of it is going to be surrounded by ciliated projections called fimbriae. So if you look down at our image here you can see we have these orange regions those are the infundibulum and then these little projections on the end are the fimbriae. And so remember the ovary and the uterine tube are not actually connected. So what's happening here is the ovary will be, you know, suspended within the peritoneal cavity and the fimbriae will kind of drape over it and during ovulation the fimbriae actually do this little waving motion and that creates a current in the fluid of that peritoneal cavity and so when the oocyte enters that fluid it gets kind of sucked up into the uterine tube through that current. It's pretty cool, right?

So that's how the infundibulum works. Now our middle portion of the tube is the ampulla and the ampulla is also the widest part of the uterine tube. And, again, ampulla is a term used pretty commonly in anatomy usually to indicate an expanded or wide structure. So I always think of how, like, an amp in music is, you know, it's going to make your music louder and bigger and that's kind of what ampulla indicates. It's like the biggest or widest, portion of a structure.

So the ampulla is typically going to be the site of fertilization. So if you look at our image here these portions in blue are the ampulla and you can see we have an egg and some sperm, meeting up there and getting fertilized and then that fertilized egg is traveling down the uterine tube. So we'll label that as our ampulla. And there are several reasons why the ampulla tends to be the site of fertilization. One just comes down to, like, basic timing.

What we often see is that by the time an oocyte has been ovulated and is traveling up the tube this way, sperm have often kind of come up the uterus and begun traveling up the tube from this direction and they just tend to kind of meet in the middle there. What we also see is that the uterine tube, particularly the ampulla, will be having like kind of little micro contractions that help propel the egg and sperm toward each other, again, having them just meet in the middle there. And also the mucosal lining of the ampulla, will have secretions that actually aids in sperm viability and motility so that can kind of aid in that process as well. So again, it does not have to be the site of fertilization but it commonly is. And then our final portion of the uterine tube is the isthmus, and the isthmus is the narrow portion of the uterine tube.

And, again, isthmus is used pretty commonly in anatomy to indicate, like, a narrowing or the most narrow part of a structure, and this will be the part of the tube that actually empties into the superior lateral or top side portion of the uterus. So these sections here, this very narrow section there, is the isthmus. We will go ahead and label that. Alrighty. So those are the uterine tubes and I will see you guys in our next video.

Bye bye.