so what i'm going to do is show you one example of each and then ask a series of questions to see if you can identify the epithelium i just showed you using the techniques i just explained so when you're identifying epithelium you really need to ask yourself two questions first how many layers of cells am i seeing and what are the shape of those cells that i'm seeing so when you're seeing one layer of cells that is a simple epithelium multiple layers of cells would be a stratified epithelium and our three possible shapes are squamous which are flat cuboidal which are squares and columnar which are columns the only slight trouble occurs when sometimes cuboidal cells they might look a little bit rectangular so in that case look at the nuclei if the nuclei is a nice little circle it's going to be cuboidal if it is an oval it is going to be columnar so on our first example we are seeing a singular layer of square shaped cells and that's why this is simple cuboidal so you're seeing that in a couple examples on this slide if you were unable to tell what shape these cells were look at the circular nuclei remember simple cuboidal has circular nuclei In our next example you're seeing the basement membrane remember epithelium always has to be attached to something and that something is the basement membrane and you have a single row of cells going off this way and a separate singular layer of cells going off this way and you can see little rectangular outlines which is how you know this is simple columnar now if you couldn't see the outlines you can also look for those oval shaped nuclei you can also look sometimes but not always you'll have these specialized little cup shaped cells called goblet cells in the next slide what you're seeing is the same type of epithelium at two different magnifications so when you're looking at it at a high high magnification you can see one layer of flat cells so this is simple squamous in this example your first instinct is to probably think that you're seeing multiple layers of cells because you're seeing multiple layers of nuclei but what you're actually seeing is you have a little short cell here and then you have some tall cells but they're all attached to the basement membrane so this is really only one layer so this is the ciliated pseudostratified columnar epithelium it is called ciliated because it has cilia on top pseudo stratified "pseudo" means fake like pseudoscience is fake science pseudostratified means fake layers and the taller cells would be column shaped in this example so this is the basement membrane down here you're seeing many cells so it is stratified and if you pay attention to the shape of the cells at the top you can see they're very flat little pancakes so this is stratified squamous even though the cells towards the bottom are more cube shaped we only care about the cells on the top when we're picking the name and this last example does not follow the naming pattern so it is stratified because there are multiple little layers of cells stacked on top of each other but they're not really squamous they're not columnar they're not cuboidal so this just gets its own name this is transitional epithelium so if you're looking at an epithelium that's stratified and you feel confused about the shape it's probably transitional your other hint is if you look at the top usually the cells at the top look like little bubbles so now i want you to think for yourself what am i looking at how many layers what is the shape so what you're seeing is simple columnar because we have a row of cells going in this direction a row of cells going in that direction and these nice oval nuclei also kind of a giveaway is the goblet cells not every single example of simple columnar has goblet cells but if you see goblet cells it's pretty safe to say it is simple columnar so the answer to what this is you're seeing one layer of squashed cells so it is simple squamous so looking at this example i'm asking about these cells here and here and here so we are seeing one layer of square cells so it is simple cuboidal so we have one layer of square cells here a basement membrane and then a different layer of square cells here they're not perfect squares they are a little dome-y at the top but you definitely shouldn't confuse this with transitional because transitional is very clearly stratified so we're seeing multiple layers of cells the ones near the top are squash little pancakes that's how we know it is stratified squamous so i'm interested in this part of the slide you're seeing multiple layers of cells because you have all those rows and rows of nuclei you don't see any cilia on top and it doesn't look squamous cuboidal or columnar so this is our transitional epithelium so this would be the ciliated pseudostratified columnar epithelium because we've got those cilia on the top which is a dead giveaway um and these cells are kind of tall and skinny with some shorter cells on the bottom now this is a bit of an advanced example but let's see if you can get it just for funsies i'm actually interested in two different things here ignore what's at the pointer pay no attention so there's this here what do you think that would be and then there's also this here and there's other example here what are we looking at so this first thing you're seeing one little layer of squashed pancake cells that's simple squamous and this even though you can't pick the individual cells apart very easily you see those circular little nuclei and they're kind of like in a cheerio formation which you see a lot with simple cuboidal so i feel like for most beginners most professors just ask you simple squamous on like a lung slide which is what i showed you before that has lots of empty space however it doesn't hurt to know what it looks like in other organs this is a kidney Alright, I hope it was helpful if you did not understand why you were wrong about anything just leave a comment and i'll try to explain as best as i can um i hope this was helpful i hope you feel great about how much you know have a wonderful day and have fun learning