 Okay, everybody. Let's talk about histology. So histology is not the most exciting, but the good news is you do not have to know it too much for the board exam. But there are definitely certain points that I'm going to talk about in this PowerPoint that you do have to know. And I'm going to go through through those with you. Okay, so I'm going to make it a little bit easier. So let me just go through the slides here and switch this up. Okay, so basically, you need to know some of the key points and I put them in the PowerPoints. I'm not going to go everything by it word for word, because you guys can do that but I'm going to try to explain it a bit easier so it makes more sense. So basically for histology, you need to know how the teeth and the tooth buds under the gums are starting to form and but try not to look into it too aggressively but just kind of know the basics such as this. So for example, when you're talking about the odontoblast, the ameloblast, kind of the different cells, this is what it's talking about. So the ecto mesenchymal cells are the odontoblast and that kind of starts with the dental papilla. So for example, okay, and then you need to know that it lies below something called the enamel organ. The dental papilla appears after eight to 10 weeks. The dental papilla gives rise to the dentin and the pulp of a tooth. So basically everything you have the enamel organ, which is where where everything sits and then you have a number of cells that help to pinpoint different parts of the tooth. We know we have the enamel, we have the dentin, we have the papilla, we have the nerve, we have all kinds of things. So this is what this is starting to talk about. So the enamel organ, the dental papilla and the dental follicle together forms one unit called the tooth germ. So the tooth germ is one unit. You need to know this. This is important because all the tissues of a tooth and it's supporting structures from this are into different cellular kind of aggregation so they go into different things. I have a couple images that might make more sense in a second, but basically the tooth germ I think everything. So the enamel organ, the dental papilla, the dental follicle are all called the tooth germ. And then the next PowerPoint here. So the tooth development or odontogenesis is the complex process by which the teeth form, sorry, I have a couple different words here that I have to fix because I keep getting confused myself. But they form embryonic cells and they grow and they erupt into the mouth. Okay, so for human teeth to have a healthy oral environment, all parts of the tooth must develop during appropriate stages. So the baby teeth start to form between the sixth and the eighth week of prenatal development and the permanent teeth begin to form in the 20th week. So these are key points to know. You know how there are a lot of people where certain teeth haven't developed properly, or they have a cleft palate, they have missing teeth, their teeth aren't very healthy, they have thin enamel, you know, thinness, thin that. Well, they might not have developed properly, they might have not developed in a healthy oral environment. So the key points to know here are the primary teeth start to form between the sixth and the eighth week, and then of prenatal development. And the permanent teeth begin to form in the 20th week. If they don't, if it's too soon or too late, this is when problems happen. So, and then we talk about the four different stages of tooth development. So there's four stages that have to happen underneath everything for these tooth teeth, sorry to actually form the teeth and the surrounding tissues, and the surrounding structures. So you have the bud cap and the bell stages, depending on the textbook, they might call it number three, number four, we talk about it being early, and then we talked about it being late. So I'm going to go through these a little bit for you guys, okay. So the bud stage is the initiation when things happen. The bud cap stage is the first time you can identify the three different parts, the three different areas, you can kind of see what's happening. The early stage is the IE, which I'll explain that makes the shape of the future crown. Everybody thinks it's the root that forms first, but it's actually the crown, believe it or not. And then in the later stage, calcified tissue starts to happen. So young enamel, but it's not fully developed yet. Okay, so this is kind of a good image. I had left the link here for you to kind of have a look so in case you're somebody that needs to see certain images, this might help you more and I found this off of I want to Pinterest, but I quite liked it because you can see how the different stages here are starting to form. Okay, so this is kind of a good one to look at. And then you have in the cap stage. Again, it's just kind of showing you different things forming. So remember how we talked about the enamel organ, we talked about the dental papilla. Well, what about the dental follicles so this is the different cells and different things that are happening at that time so I quite like this image as well. And the next stage here again, look at all the different things happening. This is when you can really start to see things coming together. So we have the dental follicle. We have the outer enamel epithelium. Look at all these different layers that are happening. I find in this bottom image, it's very prominent where the outer enamel epithelium is you see this layer here but then look at the inner enamel epithelium. And then people kind of look to it right but then you have the stellate reticulum and then the stratum inter medium so see how those are kind of close as well. These type of images have been on the board exam before so it's nice to be able to study them, look at them and really decide kind of where things are. And then another form so this is just basically showing you guys what's happening but in a different stage, the bud stage, the cap and then the last stage of course at the bell stage. So it kind of shows you different things in a different way. I don't know if you find this easier to study memorize look at or something like this, you can basically see how things start to form from the top, but then eventually things start coming together. So you guys we have the outer enamel epithelium OEE, and then we have the inner enamel epithelium you need to know the differences here remember when we had looked at this one here see how it says the outer enamel epithelium but then we have the inner. So this is kind of showing you more of the different cells that are involved. This you have to know these are the things they might ask you on the board exam. So this is just kind of a good way to show you well what does a simple cuboidal epithelium look like I wouldn't have known unless I saw this image here. So this is what it looks like versus the next one so see how it's kind of showing you. A simple cuboidal simple squamous these are hard to say, see how they look a little bit different very very slightly right and then again it's going to show you more prominent how things look here. You might have something like this on the board exam to so it's good to know the differences, but then look, see how this image here looks so much more different than this one. Okay, this is what the columner looks like so see how it's like this I don't know how else to explain it they're kind of longer right. Whereas the simple cuboidal is in like circles and it's round and it doesn't look like this. So that's kind of a good way to explain it. The stellate reticulum, these are star shaped cells. The OEE, which again is the outer enamel epithelium and the stellate reticulum and late crown development break up and there will, there will be remnants of both. So that's kind of all you have to know for this on the board exam they might say what are star shaped cells. And you can go stellate reticulum is it really that easy, yes, it can be so that's all you have to know for that one there. And then the dental lamina is there are different ones so I put those down here for you to make sure to kind of look through that know the different ones. Certain terms to remember so at the beginning when I started talking about the different types of cells, these are the terms you need to know for that so I put them in here to make it even easier. Some of them are going to be related to enamel, some of them are going to be related to denting you definitely need to know those. And then you guys the dental papilla on the board exam they like to mention dental papilla a lot for whatever reason. So these are the key points about the dental papilla that I've put in here for you. So during the cap stage, this is when you can really start to see the dental papilla. It is for the area inside the inner enamel epithelium that eventually becomes the dental pulp. When enamel formation is complete the space is no longer referred to as the dental papilla and is called the dental pulp. And even I make that mistake sometimes where I'll be talking about the dental papilla. What I mean is the dental pulp because I am I teach histology so I tend to get confused myself, but this is something you need to know you guys so I'll say this again. When enamel formation is complete the space is no longer referred to as a dental papilla. It's called the dental pulp. So on the board exam if they were talking, if they're talking about the dental papilla. So before the enamel formation is complete, the enamel has to form, you know, these things happen, but it's called the dental papilla but once the enamel formation is complete and proper. It's now called the dental pulp in the inner enamel epithelium does that make sense. So something to keep in mind. And then the different stages of the ameloblasts. This is talking about enamel. Okay, so basically you have the morphogenic stage, the organizing stage, the formative or the secondary stage, the mature stage, the protective stage so all of these stages. Now admittedly you guys they haven't asked the different stages on the board exam before, but I just I wanted to put them in here in case you want to tell them. And so you know that the, the formation of enamel doesn't just happen it takes time there's many different stages right so just something to be aware of. So where does the enamel start to form. It starts to form at the cusp tip and incisal edges so remember how I said, a lot of people think the, the root forms first, I said that right the root forms first. Well, the crown actually forms first what is the crown, that's the enamel. So it starts to form at the cusp tips and the incisal edges. Okay. So these cells are moving away from the DJ and late crown development everything's forming everything's happening. The cuboidal cells found in the late bell stage between the column or ameloblasts, the inner enamel epithelium and the the stellate reticulum so this is the stratum inter medium. This appears as a layer in the late cap and the early bell stage it seems to aid in an enamel production. So the stratum inter medium just helps to aid in the enamel being formed it just kind of helps to finish the process if that makes sense. So this is the cuboidal cells found in the late bell stage between the column or ameloblasts in the inner enamel epithelium and the stellate reticulum. Lots of different things whoops to remember as the enamel indent and are laid down with the basement membrane is caught in between two layers and actually starts to separate away. The basement membrane breaks down and is the future location of the DJ. So if they ask about the basement membrane on the board exam, you're going to know okay this is where the DJ is going to be the dental enamel junction between the dentin and the enamel meat. There was a basement membrane that breaks away but that's where the dentin and the enamel meat well I should do it this way I suppose enamel and dentin meat. So that's how that happens but it needs to break away for that to happen. Okay so crown formation remember the crown forms first so there's many different things happening. Remember the ecto mesenchymal stem cells of the dental papilla differentiate into Odontoblasts and remember it's called the dental papilla because the enamel hasn't formed completely yet once it does it is now. So the dental papilla is before the enamel has formed completely and then pre-dentin actually starts to form together and then calcification of pre-dentin yields dentin. So you need the pre-dentin to calcify for the dentin to form, which I don't know I guess it's kind of common sense because it can't form right away. Things have to start to build up, calcify and then that's when it gets thicker and stronger. Pre-omeloblasts stop mitosis okay so this pre-formation of enamel the pre-formation of dentin it takes time it is young enamel until things are completely formed. I had left you guys a couple links to look at because I find histology can be kind of confusing kind of boring. We're talking about the bud cap and the bell stages I kept it very simple in all of these PowerPoints for you okay this is as simple as it gets. But I tell my students all the time, study histology, read it over, but then kind of don't worry about it. I want you guys to focus on other things such as pharmacology, oral pathology, medical emergencies. I talk about all of this but I don't want you guys not to study histology because if you don't study histology then you're you're leaving it behind and then you're definitely going to get it wrong on the exam. You have to ask one histology question or if they ask five so you definitely need to study it study this PowerPoint understand the different types of cells look at those images to see what's happening. And that's all you have to know okay for the board exam don't look into it too much but don't not study it because then you're going to get the questions wrong. Okay, so look through that if you guys have any questions let me know, and I'll see you guys in the next one.