 In ciliated epithelium, the epithelial cells contain hair-like structures called cilia. So these are the cilia, the hair-like structures and these are the epithelial cells which can be cuboidal or columnar. So what is the importance of these hair-like structures and where are they found? So they can be found in the respiratory tract, the oviduct that is in the female reproductive system and the vasoreferensia in the male reproductive system. These are some examples of where they are found but why is ciliated epithelium found in these places? So to understand that, let's take a look at what these cilia exactly do. So let's say in your upper respiratory tract, for example, let's say at the back of your nose, there are some dust particles floating around. Now dust particles are bad for our lungs, they should not settle there, right? So the body doesn't want them there. So what does it do? It has to get rid of the dust particles. Similarly, there can be bacteria in your nose and your upper respiratory tract like your trachea or bronchi or bronchioles and also viruses and some other microorganisms. A lot of these are quite harmful to us and the body wants to get rid of them. So what it does is, it secretes mucus. Now I know what you're thinking, mucus is a disgusting substance, it's secreted by some of the cells that are there at the surface of the respiratory tract but it's actually quite useful. So what this mucus does is, as you know, mucus is a sticky substance. It traps all these dust and bacteria and viruses inside and then the body has to get rid of this whole mucus with all these trapped things inside it. It's much easier to get rid of the mucus which is much bigger than the tiny dust or bacteria or viral particles and that is where the cilia come into the picture. So the cilia have a sweeping motion kind of like a broom as a broom can be used to sweep the floor. Similarly, the cilia because of the structure, the structure is essentially the same as that of a broom. The cilia when they move, they can sweep the mucus away from the body. If let's say there is some mucus stuck in your trachea, the sweeping motion of the cilia will move the mucus upwards away from the body or if it's at the back of the nose, then the body will move the mucus forward so that it goes outward towards the outside of the nose. So when the cilia move, when the cilia move using their sweeping action, the mucus moves outwards away from the body. So this is what happens in the respiratory tract. Now let me show you another example of what happens when cilia move. Let's take a look at what happens inside an oviduct. So you know that every month or let's say every 28 days, the ovaries of a woman release one ovum in one of the oviducts. So that ovum is released at the beginning of the oviduct and it has to be propelled forwards towards the uterus. Here again the sweeping motion of the cilia come into the picture, the cilia sweep and sweep and the ovum moves and moves and moves towards the uterus. So this is all that is there to know about ciliated epithelium. This is how the cilia function whether to propel mucus or ova or something else, let's say sperm in the male reproductive tract. This is pretty much all the cilia do in ciliated epithelium.