 Epithelial tissue has various functions, protection, absorption, propelling things along, like mucus. One of the very specialized types of epithelium is glandular epithelium, in which the cells of the epithelium arrange themselves into a gland, and the gland is involved in a secretion of a particular substance. So this video will take a look at the different types of glandular epithelium. Based on how many cells the glandular epithelium has, there are two types, unicellular and multicellular. The most common type of unicellular epithelium is the goblet cell. So this one right here is the goblet cell. It is present in different places, such as the digestive tract, the respiratory tract. Its job is to secret mucus at the surface of the epithelium. Why does it have such a weird name? Because it's shaped like a goblet. A goblet is a glass like this, which is wider at the top and narrower at the bottom, and this is exactly the shape of a goblet cell. Hence the name. The multicellular types of glandular epithelium are, of course, made of many cells. Be it unicellular or multicellular, glandular epithelium can be classified in another way. It can again divide it into two types, exocrine and endocrine. Let's look at these types in detail. So both of these types of glands, exocrine glands and endocrine glands, they start out with a regular epithelium. So in any epithelium, there is a surface at the top. So this is the surface. It faces different things. It can face the exterior like the epithelium on the skin or it can face the digestive tract, like the epithelium lining the digestive tract. Then it can also face the respiratory tract. It can face the excretory tubules in the kidneys. So that's the surface of the epithelium. Always has a surface and it also has a basal part. So both the exocrine and the endocrine types of glandular epithelium start out with a regular epithelium. And then what happens is, they start growing downwards away from the surface. The side that does not face the surface, that's where they start growing inward in order to form the gland. Now in the beginning, the exocrine and the endocrine types of glands look the same. They start growing inwards, grow further and a gland is forming in both cases. And then they form a shape such that there is the space inside. It looks like a tube. And for both cases, exocrine and endocrine, they are there and the space is called the duct. And both of them have this and this duct stays in the exocrine glands, whereas in endocrine glands, they disappear. We will come to that in a bit, but first let's concentrate on the exocrine glands. The exocrine glands are the glands with ducts. So all these cells that you see that line the duct, they are the ones that secrete the substance, whatever they're supposed to secrete, depending on the gland. And they collect in this duct and then they are sent out, outside, wherever outside is. Skin or as I said, digested tract or whatever else it is. So that's where the secretion is sent through the duct. And where do we find exocrine glands? At different places in the body, for example, sweat glands are exocrine glands. Then there are sebaceous glands which secrete oil. Then there is, there are the salivary glands which secrete saliva in our mouths. And then there are digestive glands which secrete digestive enzymes in our digested tract. All of these are secreted by different exocrine glands. Now let's take a look at what happens to the endocrine glands. Initially they have ducts just like the exocrine glands, but then when they keep developing, the duct disappears. And then, see now how they've lost touch with the surface. The exocrine gland is always in touch with the surface but the endocrine gland does not have a connection with the surface anymore. But they have to secrete their substances somewhere, right? For the exocrine gland, it was very straightforward. They just secreted the substance into the duct which led the substance outwards. What does the endocrine gland do? They secrete their secretions into the blood, the bloodstream. So what happens is when the endocrine glands are fully developed, blood capillaries, they go through them. And whatever the gland secretes, they go into the bloodstream via these capillaries. So the endocrine glands, they secrete their substances to the bloodstream, whereas the exocrine glands secrete their substances to the ducts. Now what are some examples of endocrine glands? All the glands that secrete hormones like the thyroid, pancreas, the adrenal glands, all the hormones that are secreted in our bodies are secreted by endocrine glands. So we've seen that glandular epithelium can be divided into two ways. In one way, we divide them into unicellular and multicellular glands. And the other way of dividing glandular epithelium is into exocrine and endocrine glands.