Thank you. Hello, do you hear me well? Yes, very well. Okay, thank you. I got your headset working. So let's see. I think we are still a little bit early. No, Harris Mann is not a new resident, is he? No, you are not. But all the others of you are now new? Yes? Welcome. It's exciting. And you started now or during the summer already? So I started the end of June. Okay. But did you attend any histo sessions already? Yeah. Yeah, I've attended a few. So starting to get head around some stuff, but still a bit scary. Okay. Because right now we start really very basic. I mean, it's really structure of the skin right now. Yeah. That would be really helpful. And the others? I'm also new. You're also new. Super. I started in September. Oh, that's really new then. I don't see names which are familiar yet. Yeah, that's right. And Thursday, this date or this time, is good for you? Yeah. Okay. Yes, it's perfect. Okay. Super. I think we wait another two minutes to start. And we will have all together, I think it's six hours or six sessions now, just with the normal anatomy of the skin. I think this will be sufficient. So today we just really do the very, very basics of four different, five different species. And then next time we'll go a little bit deeper. So, Monika, one question. Do you record this meeting? Yeah, right? Yes, I do. Okay, perfect. Sorry, I was late. And then I asked questions. No, but I have to check again. Because when I invited to the Zoom meeting, I said recording. Yeah, so I should record it. No, it's recording. We can see it. Okay, super. Yeah, yeah. I think we said that in Bilbao so that some of the Asian residents can listen to it. Yeah, yeah, yeah, yeah, yeah, yeah, yeah. That's super great that you start this now. I wanted to talk to Sonia if you had a consent in the end about it. And if you are going to start this or not, but I couldn't talk to her yet. So, it's okay, nice. Then you start this now. Okay. You are not a first-year resident, though. I think this is a bit easy today. That's correct. But it's always nice to see who's here. And maybe I will leave it running a bit on the side and you can always learn something. And you hear me well, huh? Yeah, yeah, yeah. We hear you well. Let's see. Is it more comfy than the other one? It is definitely more comfy. No, just because last time you said it still was a little bit disrupted, although I had a headset. Yeah. Let's see how this meeting goes. Yeah, okay. Okay, nice. Have fun. Yes. So, welcome, everybody. So, it's really nice that you are all here. And I hope you will learn a little bit. And it will go better and better each time. I'm pretty sure about this. I am sure about this. Anyway, now I have a few slides discussing different species anatomy. And I mean, the long-term goal is that you present the slides and tell us, not only me, what you are seeing. Now, for the beginning, I'm not so sure if this makes sense, because if I present the slides, then I have the option to point at the different structures. So, I don't know. So, I don't know. So, is anyone of you, does anyone want you to start presenting, or shall I open the slides? It's up to you. You are the bosses here. I think you can start presenting, and then we will see how it's going. Okay, so, I'll open the first slide. Just hang on. Oh, the Zoom doesn't want to open. So, this should be the first slide we want to discuss. Now, I would like to do this as interactive as possible. So, don't feel shy, because, I mean, you only can learn, also, if you say something wrong, huh? So, it's always good to say something and be actively participating. So, does anyone of you have already an idea of what we are seeing here? I mean, we are obviously looking at skin. But, which layer is this here, the upper layer, the uppermost layer? Stratum corneum. The very uppermost is the stratum corneum, that's right. And the stratum corneum is very often later on described as being hyperblastic. So, too much stratum corneum, which is not always right. So, the stratum corneum really can vary depending on the grooming of an animal, on if it is brushed regular layer or where it is living. And so, this stratum corneum can really be thick like this and still be normal. Be careful saying it is too much. So, then we have this layer here. What is this? Stratum spinoso. Yes. Let's see. First of all, this all together is the epidermis. And then, let's start from the top to the bottom. So, this is the stratum corneum. We had that already. Then, there comes the next layer. Stratum granulosum. That's the stratum granulosum. And then, we have the stratum spinosum. And then, at the very bottom… Atum basale. We have the stratum basale. That's right. So, do you know anything about these different layers? So, the first layer of stratum corneum is often described as non-viable parts. So, there's from down to up. It loses its cytoplasm nuclei. And then, gets this… It's a conification. So, it's a part that's where it's conified. Conified. And then, not… This is not a living part anymore. If there are nuclei retained, we talk about a pathological process. Then, we have this stratum granulosa. Which is usually a very thin layer. And very often, not that visible than here, right now. Do you know anything about this layer? It's mainly the layer that contains hyaline granules. Which type of hyaline granules? I don't know. The keratohyaline granules. This is important because the trichohyaline granules you see in the hair follicle. In the inner root sheet. That's why it's important to specify them a little bit more. Here we have keratohyaline granules. They are, if the staining is good, they are bluish. They have this bluish tinge. This is the same granules as you see also in the interdipulum. And then, this is the layer, very thin usually, in which the quantification process starts. Then, we have the stratum spinosum. Where does this name come from? Any ideas? I think we see it here. It's because of the spinous lines here. They look a little bit like a leather. And then, in between, I think we'll see it better in other slides later on. Like here, perhaps. You have the steps of this leather. And these steps are the spinous things. And this is the layer which gradually matures towards the stratum corneum to the coronification. And then, we have the basal layer. And the basal layer, do you know anything about this one? It's normally a layer that is around one cell thick. And there are the stem cells. So, from there, everything develops upwards. Not every basal cell is a stem cell though. But these are still pre-impermined, very actively proliferating cells. And it is assumed that like every 20 cell or so, it has stem cells or at least progenital cell properties. And then first divides to the sides. And then upwards. So, these cells terminally differentiate towards the cells that are coming from here, going upwards, terminally differentiate with the stratum corneum cells to this corneal side. And this epidermis is held together by appearance junctions and also other molecules. And they are the most important ones, for us at least, are the desmosomes. And in this spinous layer, that's what you see here are the desmosomes, are these latter steps. So, but then there are other cells, for example here. Here you see a mitotic figure. This is a dividing cell here, where the nucleus is really condensed. Then there are other cells within this epidermis. Do you have any idea which cells these could be? Melanocytes. The melanocytes. Do you know where they are located? In the basal layer? Yes, and most likely these are these cells here. I mean, without special stains, we cannot identify them for sure. But with these cells, which have these vacuoles, are most likely the melanocytes. And they, if you look at them in special stains, they have really these long dendrites, which go in between and into the neighboring cells. And then practice out their melanosomes into the neighboring side. And the melanosomes are these organelles, which contain the melanin. So, the melanocytes themselves, they are only located in the basal cell layer. That's correct. But the pigmentation may be seen also further out. Then there are other important cells in the epidermis, which we cannot appreciate. The langerhang cells? Dendritic cells? Yes, the langerhang cells. The langerhang cells are epidermal dendritic cells. So, both answers were right. And do you know which function these cells have? They present antigen? Yes, that's right. They take antigen up and present it. So, every antigen which comes from the outside, for example, pollen or mite antigen, etc., flea. Now flea may be biting deeper, but pollen or mite antigen, they are taken up by the langerhang cells and then presented by them. Okay. And then there are other cells, or at least enders of cells. We have many- Merkur cells? Merkur cells, for example. Exactly. So, we have the endings of- Merkur cells are also located in the epidermis, but there are also other nerve endings have their endings in the epidermis, and they make the sensitations, etc., for example, that you are sensitive. Okay, then we have the epidermis, and the epidermis is connected to which structure? Collagen? Yes, but the overall structure, how do we call this? Dermis. Dermis. So, and the dermis is anchored to the epidermis by a specific structure, which is very strong. And how is this structure called? Could you please repeat the question? I didn't catch it. So, the epidermis is anchored to the dermis by a specific structure. How is this structure called? The hemidesmosomes? Yes, or the hemidesmosomes anchoring filament. Right, and this is mostly located anatomic in which layer. The basement membrane? The basement membrane? Yes, exactly. This is located in the basement membrane. We see it not very well in the HSEs, and in the next slide we will see it. Okay, so then we have the dermis. The dermis, you said already, is mostly composed of collagen fibers. What other structure do we have in the dermis? Do you mean like something like the adnexia, like the glands, for example? Of course, of course, but I wanted later, but like here we have the lymph vessels and the lymph vessels, for example, you can very easily appreciate by these, they are usually empty, but they have also this endothelial lining. So these flattened nuclei surrounding an optically empty space. This is, for example, a lymph vessel, this is a lymph vessel as well. And also blood vessels, here you see an erythrocyte in a blood vessel. Look, they are not very well depicted. Here you see, for example, papillaries, you know, you see the red cells, these are the erythrocytes. And then we have this lumen, which is again surrounded by this endothelial cell. So we have blood vessels and lymph vessels within the dermis. We have our cellular material, which is the extracellular matrix between the collagen fibers. And then we also have fibroblasts, which are these elongated cells, which have also these elongated nucleus, but they don't line a lumen. They are also present in the dermis. Then we have around the blood vessels, we have some, it's not a good example because we have more cells than normal, but usually these blood vessels are also surrounded by few lymphocytes and also mast cells, which are normal in number. They are normally present within the dermis and belong to the dermal immune or skin immune system. So these are localized cells around the blood vessels, which are ready to take off once they are needed. So the neutrophils and the eosinophils do not belong to the skin immune system. They only come out of the blood vessels when they have the respective signals. And then we have the adnexa and the adnexa are associated or are composed of which? The hair follicles? The hair follicles, yeah. They may be in different stages and we will have an extra hour to discuss them. But this is a hair follicle, for example, here. They are oriented vertically from the epidermis to the subcutis usually. Then the hair follicles are associated with other structures. The sebaceous glands, yes, I'm just looking for one. Here we have one, but it's also associated with the hair follicle. The sebaceous glands and the sebaceous glands are usually composed of material sebocytes and surrounded by a layer of basaloid cells, like in the epidermis. So these are the cells that mature towards the sebocytes. Then we have another tissue, like here, for example. What glands? What glands? These are the glands, the apocrine glands, yes, or epitricle glands. We also may have apical or acrine glands. They see on the dog's nose, for example, or on the footpath. They don't open into the hair follicle, but they open directly to the epidermis. So these are cells. And then we have another structure, like this here. The erector pili muscle? That's the erector pili muscle, yes. And then we have the deepest layer of the skin, which is this here. How is it called? The hypodermis? The hypodermis or the subcutis. That's both correct. And that is composed on most body sites of mostly fat lobules. So these have two fat cells, and they are encircled in this fascia type or in this fascia. You see that here they are looking a little bit like fibroblasts or like fibrocytes or elongated cells with a thin elongated nucleus. So these are the fascia. And they are holding these fat cells together. Of course, within this fascia, we have also nerves and nerves and blood vessels and lip vessels. And then, I mean, if we are lucky, we see, especially in the hypodermis or in the subcutis, we see also these bigger arteries and also, of course, veins. And then we have it may be separated by thin muscular layer. Another layer which is also composed of fat before and the mass of the real muscle layers of the body are coming. So this fat layer is not present everywhere. It is not present, for example, on the legs or on the head. There we have more connective tissue and if we, if you have alternate on the ear. So if you have biopsies from a head or from from the distal or from the distal legs, you will not see this fat layer. It is more pronounced on foot, for pets, etc. And then we can come here to the species. Have you an idea which species this could be? Not many hair follicles. Yes. So this seems to be a single hair species? Simple. Yes. You don't say single, but simple. Yeah, simple. Yeah. So it's a simple hair species. Yes. Do the others know what that means? Yes. Yes. No answer, it's not as well. Simple hair follicles mean that every single hair follicle has its own opening through the orifice to the outside. So every hair shaft has its private infidibulum. So this is the infidibulum, this is the hair carp, and so it comes out here. From this hair follicle, it comes out here. From this hair follicle, it would come out here. And this is, of course, not always perfect. So it's, that's right, it's a simple hair follicle species. And amongst our domestic animals, which are simple hair follicle species. Horses, cows, and pigs. Yes. And which of them has the least hair? The pigs? The pig, exactly. This is a pig. Because we don't have many, I mean, it depends on the breed there as well. But anyway, they usually do not have much hair in comparison to the cow or to the horse anyway. So this is a pig. And the pig has also, like humans, in contrast to a horse or a bovine, which have, if they are completely healthy, very irregular epidermis, the pig has this little ribbit. And this is usually present and normal in non-haired skin. Or in poorly haired skin. That the epidermis is not absolutely irregular. So yes, this is a pig. So yes, this is a pig. Do you have any questions to this slide? When do you say that the dermis is thick or thin? How do you? Good question. This is really, I think it's a, it's a question of experience. In most species, it is like this, that the adagin bulb of a hair follicle is reaching into the subcutis, whereas the telogen follicle, like here, ends in the dermis. So if it is like, like here, you can say it's about normal, normal thickness of the dermis. You will see if it's too thin. But it is really also a question of, yeah, it's of experience. But it is not very often. There are a few diseases where the dermis is too thin. This is mainly Cushing's in the dog, really, or really severe wasting diseases, anorexia. But otherwise, the dermis usually has a normal thickness. It's rather the epidermis, which changes its thickness. Okay. And between the species, I saw that compared to the cat and dogs, horse, cattle have more thicker dermis. That is true. And they have a very, very, they don't, they have less subcutis. And more dermis and the hypodermis, where the adagin hair follicles, for example, go really. But we look at them. I have a small question. What confused me in this slide, because I thought it was a pig, but I thought that the ridges would be more prominent. That's why it got me confused. That's the difference between the book and the reality. I'm sorry, I cannot answer you this question. We look at three different pigs now. You may see that there are slight differences. And I cannot explain to you why it is thinner here or not. I really cannot. Thank you. Sorry. But what you can, nevertheless, I think you can recognize that it is a pig based on the fact that the thread glands are quite dilated and have a very, very flattened epithelium, like here. I mean, if you would not know that this is epithelium, you also could think about this being endothelium. I mean, it looks a little bit thicker. But nevertheless, it's really thin. And then the other thing is really the scarcity of the hair follicles and this rata pecs, which we see. Then we go to the next one. You should see it. Do you see it? Not yet? You should see it. Do you see it? Not yet? No, not yet. Yeah, no. This is the very same pig here. The same two actually, the same slide, but it's just the PAS stain. The PAS stain is used to demonstrate the basement membrane. And it is still not beautiful, but I think you can see it. This is the red line here or this pink line. And this is this basement membrane, which has contained most of these adherence junctions. The hemidesmosomes are located in the basal cells. And through the basement membranes, we have these molecules that connect the hemidesmosomes the underlying collagen of the germies that you can see. Unfortunately, it's not always as nice to see. The basement membrane is also surrounding the hair follicles, but there it's usually not easier to see. And it's also surrounding the sebaceous gland and the sweat gland. And it is a stain, which is often used, for example, if you have any blistering diseases. But as I said, it is so unreliable staining itself that you hardly can use it. Here you see it's nice around the hair follicle. Yeah, this red line here. Okay, that was otherwise the same slide. And then we can go to the next one. Okay. So this is another pick. And this looks more ideal. Don't you think so? The person who was asking before about the ratipex. Yes. That's what you would like to see. And then it makes it clear. But you may see here that this pig has also less hair follicle. So it may well be that the other pig, which we looked just at, had too much hair follicles. And that was why the epidermis was not as typical. I think other than that, we have discussed most of this slide already. I mean, we see the ratipex here in the pig. And we see that mostly there are no hair follicles. We have the sweat glands. They are located very deep down. Here and here, they look a little bit more, not yet cuboidal, but like epithelial cells. You see that? But they still have quite a wide lumen in comparison, for example, to the horse is a drug. And then here, the subcutis is also not as thick as in the other pig slide. There is maybe a body location where the fat layer is not as prominent. Or it may be a younger, a younger animal. I'm sorry, I don't know who is the animal, which, where these animals are from. But you see the variance here, hmm? Okay. So then we go to another species. And then we go to another species. Oh. Oh. Oh, la la la. Sometimes my bowel is too fast. So, ah! Anyway, sorry. But you see the slide? Not yet. Still not. Okay. And could you tell us which slide the numbers are? Yeah, it's the one with a hundred. Of course. That is the B-17-100. The former slides were the B-454, B-456, and B-457. Thank you. And now this is the B-17-100. Oh, what do you see here? There's lots of hair follicles and they are simple hair follicles. Yes, look again here, one hair shaft goes out through one infundibulum here as well. They are much closer together, but they have only one individual infundibulum each hair shaft. Yes? Yeah. Then, what else do we see here? So, looking at the sebaceous glands. So, yeah, I had a look at this one in the group. But having a look at the sebaceous glands, all the vacuoles in them were quite similar in size. Yes. So, quite neat from what I could see. And then, looking at the apocrine glands, I thought the lining of them had quite cuboidal cells, which were also kind of hazy and quite prominent cuboidal cells lining them. So, I thought this was the head skin of a horse. Yes, absolutely perfect. Yeah, that's right. This is typical for a horse. This is really abundant sweat plants here. And they have no other animal has such cuboidal lining of the sweat of the sweat plants. And they are quite numerous. And, nevertheless, the lumen in comparison to the pig now, or you will see it later also for the bovine, is rather small in comparison to the other simple-haired species. Then, just, I mean, we were before talking about the melanocytes, which are in the epidermis. And I think here you nicely can see the melanin pigment, which is here distributed between. From one melanocyte, it is really transported through the androids to the neighboring basal cells here. And also, then, if they proliferate, it is also transported. These melanin granules are also transported upwards. Upwards. Then we see what else is typical for a horse, for example. I mean, we see here the blood vessels. Here, for example, the aristocytes are a little bit pale. But if you look at low magnification, at a horse biopsy, you always get the impression this dermis is busy and there is inflammation going on. And this is in many cases not true. A horse has very, very prominent parasites. This is one layer of the blood vessel. These are all these cells here. Yeah. These are not inflammatory cells, but these are parasites. And this is why a horse dermis looks often very busy, although it's not inflammation. This is something you really have to keep in mind when you are a biopsy of horses. Here you see it quite well. I mean, all these cells with this elongated nuclei here, these are no inflammatory cells. These are just parasites. And another thing about the horse is that the mast cells, like in the bovine, they are not as easily to see as they are in the dog and cat. You often need a special stain to depict the mast cells or to say, this is a mast cell in a horse. You are in a normal eating training. And what else did we say already? That the subcutis in the horse is usually not composed of fat, but it is composed of collagen fibers. Here, this is thinner. And here, the dermis, those you can appreciate here that the dermis, this is all the mature collagen fibers of the dermis. It's the same type of collagen as we see here in the upper dermis, so this thick fiber. Whereas here, then, you may appreciate that the fibers get thinner. Can you see this? That there is really a difference between the thickness of the fibers, and this is then the hypodermis here. So, a horse usually doesn't have this rich fat, as we see. I mean, probably there are horses who have a lot of subcutaneous fat, but never as much as a dog or a cat, or not as much usually. But the dermis is much thicker. So, as I said to you before, normally, the additon hair follicles, and I have to look if I see one here. There is no additon hair follicle here. But they usually don't get deeper than underneath the eccrine gland. But the dermis get much, it's much thicker. So, the hair follicles are completely embedded in the dermis, also in the allergen stage. Do you have any questions to this slide? No, perhaps one more thing, because this is also some often interpreted wrong in the horse. The stratum corneum looks always more laminar and less basket weave. So, don't say this is a laminar autokeratonic hyperkeratosis. This is just normal here. If it's a little bit more compacted, then we see it in the dog. Okay, then we can go to the next slide, which is the B1846. Today, my computer is really slow. So, now, what is this? Yeah. Any idea? Can you hear me? Yeah. So, for the epidermis, I said we have a thin basket weave stratum corneum with no orthokeratotic or parokeratotic hyperkeratosis. Yes. The epidermal layers appeared unremarkable. No spongiosus or ulceration, the dermis shows normal collagen arrangement without fibrosis, edema, or inflammation. We've got multiple compound hair follicles, and I thought we were dealing with canine skin, but I'm not 100%. No, that's not wrong. All the rest was fine. Okay. Look, for example, at this sebaceous gland here, huh? This is a typical sebaceous gland of a cat. So, a horse is a big cat, I was taught when I was a young pathologist, and this is true. Their skin structures are very often a little bit alike. Also, their reaction pattern. And the horse has also these fine vacuoles in the sebaceous, very regular. And this is here, the same thing. So, this is a horse. Again, here, the basiloid reserve cells. Then, as you said already, we have the compound hair follicles. And for those who do not see this as or not know this as well, they are closely sitting together. And here, you can appreciate that this hair shaft comes here out, and this hair shaft comes here out, and we do not see more here. But this is like they all end up in the very same orifice or ostium towards the outside. So, they share the ostium, huh? And this is why they are called a follicular compound. And another hint why this is a cat are the mast cells. The mast cells of a cat look like a fried egg. Here as well, or here as well. First of all, they are often a little bit arranged as groups. And they have this slightly essential nucleus. And then this, they are roundish. And then they have this granulated cytoplasm. This fried egg appearance is very typical for the cat mast cells. If you are not sure about the sebaceous clans, then look at the mast cells. They look different in a dog. So, here again, this is a location where the adagin follicles are located still in the dermis. So, this must be head or leg. The subcutaneous only is deep down here. It's really depending on the body size. But what you otherwise see nicely is this group of hair follicles. Again, a reptopili muscle here. And the fable side, which has very equal vacuoles. Are there any in the sweat glands? I'm just looking for the sweat glands. They are also a little bit boil here. Like in the horse. Not as pale as in the horse. But otherwise, a little bit similar. Any other... Do you know what this is here? This structure. Not sure. Could that be a nerve? This is a nerve. Yes, exactly. They look a little bit like... I mean, you see here these long nerve fibers or the compacted sheets. And then the neurons are the neuron and then the nuclei of the nerve cells, huh? Yeah, this is the nerve. I think other than that, we have described more or less everything already. Okay, so we can go to the next slide. Groups. Just... Yeah. Now this is the... 51, B1851. So, who wants to say anything? I cannot see it. I can't see it. I have no clue how I could speed up the screen sharing, really. It's working now. Yeah. So, I sort of, at first glance, just thought it was very densely haired. And when I looked closely, I felt they were the simple hair follicles, because they each had their own individual osteo. Yeah. And they all have their own sebaceous gland and apocryne gland, sort of, per hair shaft, I think. Yeah. Yeah. The sebacites, similar to the horse, had their small uniform vacuoles. Mm-hmm. Mm-hmm. And I also saw some erector peely muscles. Yes. In amongst the hairs, because they're quite close together. The... The other one? The other one? Yeah. Just on the side. And seeing the horse dermis, this looks slightly less busy, but... The apocryne glands have a more flattened epithelial lining than the horse, and the lumen just therefore maybe appears wider, and they don't look as tortuous as the horse. Mm-hmm. And I felt they were perhaps more alongside the hair follicle than underneath, you know? Yes, that's right. That's right. I don't know. I mean, there are very few really detailed anatomical descriptions looking at species variations. So, I'm not sure if I'm right, but... And you do not get to see that many horse and at least bovine biopsies. At least I didn't see that many. So, I'm not sure if this is really a statement we can make, but observation or impression I got over the time is that this is true, that in the horse they are often here located deeper down and not so much alongside, but I'm not sure if this is really true for all body size. And I did think that the epidermis looked a bit thicker than, like, sort of the cat. And we see that here as well, huh? Yeah. Okay, and other than that, yes, your observation was right. The number of parasites is not as high as in the horse. I still have the impression it's a little bit, that this is more prominent than in a dog or in a cat. Also here, I'm not sure if it is just by impression. Or is there really literature for it? I have never found anything. Also, if you look in the anatomy textbooks, it is usually not so much described in detail for the different species and different body location. Okay, and here, one more species again, for example, the nerve. Around the hair, you see quite many nerves in any species. But also here, you see them more often in the horses, in the bovine. Perhaps they are more prominent, I don't know. And then again, here we have a very, very thick germis. And hypodermis here, which also has some muscle, muscles here. You see that? These are muscle cells. Or if you, you know, an animal moves the, if a fly sits on it, for example, they can move the skin. This is made by these muscles here. Okay, any questions to this one? I was just wondering, I couldn't find normal for goat or sheep. But I was wondering how you tell those apart? Or like, if it's on the face of a sheep, if that's also got simple hair. I honestly, I cannot tell you. Okay. Okay. Fine. I have only, there is also no literature really on it. I would love to see, for example, from different, because I'm interested in the hair follicles, I would love to see different biopsies from different body sides of a sheep. And look, if on the breed, and the breed, the only thing, only biopsies I've ever got from, from goats mostly, where the parakeratosis biopsies, or some viral infections, and then it is not normal anymore. I have no, no experience of that. Okay, thank you. And I also have no, I could provide you a rhino and an elephant, but not a sheep or a goat. But if you are from the UK, you probably may get more of these. I think they do see them, but maybe just not normal skin, trying to get a normal sample. Yeah. And this is just a bovine again. And I only wanted to show you that one because it happens, unfortunately, very often that you receive biopsies, which are not oriented perfectly. They are still not lost biopsies. And I use this to show you how the hair follicles look. If you do not orient them correctly, they really look like donuts. You still can tell the cycle stages, but we have that in another section. But what I would like to tell you here is we have the simple and... You cannot see it at the moment. You cannot hear me? And not see it. Sorry, again. Now you can see it or not. Yes, thank you. Yes. So, as I said, the only thing which I would like to tell you here in terms of anatomy, we know that we have simple or compound follicles. And I think during the evolution, the hair follicles were arranged in a group-like pattern. And I think this is something we may appreciate here, that this is, for example, a hair follicle group. This is a hair follicle group. This is a hair follicle group. And these groups are usually made of three hair follicles. At least this is written in the textbook. I think sometimes this looks like four. But anyway, you can see that they are slightly grouped together. I don't know if you can appreciate this in this slide. This is something I wanted to mention here. This is a group together. This is a group together. It's not always perfectly grouped. But it is written in the textbook. And I think this is meant by this grouping. That's about it, what I wanted to say. It's not. We still have another one. And now we have the 1859. Finally, the space, yes, you will most. Clearly. So, what do you see here? Well, I wrote down that there are baskets with stratum corneum. Maybe a bit hyperkeratotic. Yes. Sure. The epidermis is quite unremarkable for the dermis. I wrote down that we have a lot of collagen that is parallel to the surface. I felt like it's a bit damp, the collagen I'm saying. I think it's normal, huh? And just, may I just interrupt you, just to tell that all of you now, huh? This is a normal thickness epidermis, huh? So, epidermis, this is not atrophy, huh? Because it doesn't look thicker in the dog if it is normal in a normally-haired body site. May have a few more cells like here, and this may be a artifact here that looks so thick, but this is a normal thickness epidermis. And do you know what this is? This is thicker here. I'm not sure. This is such a tilatric pad. This is where you have many, many nerve endings. This is, and this, they look like this, huh? They have this mootinous ground substance. We have many, many nerve endings in here. And the epidermis over this tilatric pad is thicker, but regular than normally. You may see it in areas which are extremely, they are especially touch sensitive here. This area. Just that you know how they look like. You don't see that very often in a biopsy, but here you have it. Now, sorry for the dermis. I felt like the hair particles are compound with a lot of anagen phase. And for the serbaceous glands, they had vacuoles of varying sizes. So this is why I thought that it's probably a dog. It is a dog. Yes. I also, maybe there are some hair follicles that had a lot of triculumel keratinization. I am not sure. In the infundibium, you mean? Yes. It's not triculumel keratinization, no? It's infundibium keratinization. Okay. So this is what I wrote down. Yes. And you see here, again, that the anagen hair follicles. They are going down into the tissue of the saputis. And this was a dog which was not extremely fat. So this is then the normal saputis layer. And then we already have the fascia here. Again, here, just to point it out once more, that's a nerve fiber. Here, also here, this is a nerve. And this is a nerve. This is a nerve. Because usually we do not pay too much attention to them. But they are there. And yes, I think this was it, huh? I mean, in the dog, I think it is sometimes not easy to see the stratum granulosum. It is nevertheless there. But it is very often, if it's not hyperplastic, it is really often not easy to see. Yeah. Do you have any? I have a question. Yes. Just to the, just this one piece with the pad. Is it like the part with the nerve or that the epidermis, there is thicker itself? Like the epidermis is the pad or the part where the nerves ends is called like that? I thought it is a combination of both. Okay. And nerve endings going into the epidermis. But I think it is the entire structure, which is, at least to my knowledge, which is called tidal-truth pad. Okay, thank you. Any other questions? Perhaps we didn't look at the, just to finish up, at the sweat glands in the dog. You see that the lumen is not as large as in the boboil, for example. They have like, not cuboidal, but close to cuboidal epithelial cells. Sometimes they may be very, very flat as well. They don't look as prominent as in the horse, in the, in the, in the height. And they are not as numerous as in the horse as well. But this combination of these sweat glands, and these siebecides and the fact that we have compound hair follicles makes it a dog. Okay. Any other questions? Could you show us again the leucocytes around the vessels? Yes. Like, for example, here, these are mostly lymphocytes, I guess. And also dendritic cells here, the small ones, are the lymphocytes. And then here we have probably a few dendritic cells. It's, you have, that's the skin immune system, it is called. I mean, they're not numerous, but they are there. Like here, for example, also, there are a few dendritic cells. The endoth, or I can go to them, just hang on. It would be probably easier to see them if we would have, for example, a CD3 stain. But you can, we have most likely a mast cell. Here, this is a mast cell. Then here, we have a few lymphocytes. Here, the molar nuclei, these are the lymphocytes. And then the cells, which have a little bit lighter nucleus. These are the dendritic cells, the dermal dendritic cells. Here, we have a mast cell again, for example. Here, this is a mast cell. Here, these are endothelial cells, but this is a lymphocyte again. Then, these cells with really elongated nucleus along the collagen fibers. These are fibrocytes. About the mast cells you showed, it also looks like a fried egg. So, the fried egg is for the cats and dogs, or not? Yeah, they are a little bit longer in the dog. But I agree. Here, this one looks very rounded. Perhaps it is a bit activated right now. The typical fried round egg is more the cat than the dog, for sure. But yes, I agree, this one didn't read the book. Okay, thank you. I'm sorry. But you will see, over the years, you will see more mast cells. Like, for example, this is a dog mast cell as well, probably. And that looks different again. Yes, okay. It looks a little bit more elongated. They usually also have more granules in the dog. Like, these are mast cells as well, these two. And this is a dog mast cell here. Okay, any other questions? Here again, a blood vessel, a blood vessel. Here and here. This is probably a limb vessel here, where we do not have any erythicite in the lumen. This is a capillary again. Yeah. Anyway, yeah. Any questions? What the different species gland between canine and feline? The enducidensis gland? As I said, the dog has this very irregular vacuoles within the sebocytes. We have this huge vacuoles. We have this size vacuoles. We have this small vacuoles. So, in the dog, this is very, very irregular. And then, if we go back to the cat again, that would be the B1846. Do you see it? The B1846. Do you see it? The cat? Yes. Yes. Yes. Okay. And this, oops. In comparison, it's the cat. And you can see that here, the vacuoles are very, very similar to each other. It's not always perfect, but overall, the cat has very equal vacuoles, whereas the dog has really very irregular sized vacuoles. This is the difference. Yeah. Thank you. You're welcome. Any other questions? Yeah. Hi. Hi. Yeah. Yeah. So, just wanted to ask the difference between the basket weave and the lamina. How do you differentiate? This will be in one of the next hours. Okay. I briefly can, of course, tell it in the basket weave. You see these individual corneal sides as the single layers. And in between, you have this optically empty space. That's the basket weave. Okay. Whereas, you know, this is a, by the way, this is a corneocyte, which has been just flipped around. This is one corneocyte. This is one corneocyte. They are flipped around and then they appear like this on the epidermis or as the last layer of the epidermis. And if they are individualized, they have this optically empty space in between. And if they are a bit more compacted, like here, then it is, you would call it more lamina. Although the deepest layer of the stratum corneum is always more compact, like here. So that is very normal. You would not call this a compact hyperkeratosis. It's these layers which count to describe them. Okay. Thank you. You're welcome. Any other questions? No? Okay. Then see you in a month. Or in Toulouse. Oh, in Toulouse. Yes, of course. If you are coming, yes, of course. So, bye-bye. Thank you very much. Thank you. Good, good traveling to Toulouse, then. Bye-bye. Bye. Thank you very much. Bye. Bye.