So, in this extra resource, I'm just going to show you some more examples, some more images of the key structures that we were talking about when we were looking around the histological section. Because the more times that you see things, the more familiar it starts to become for you. So here we return to the cat skin and again this is a low power view just showing you again the location of the epidermis here on the outside of the skin being pointed out by this arrow here. The other thing I wanted to point out on this slide was the appearance of the fat cells on a histological section. So we said that the cytoplasm of these cells does not stain, which is why this looks clear here. Because the fat that was here has been lost in the processing of this section, and so it doesn't stain. But what you will see is a delicate line around the outside which is marking the cell membrane of that particular cell. And you will also see every so often a more darker blue round or oval structure, that's the nucleus of these individual fat cells. The other thing that's being pointed out in this section here is the base of the hair follicle. We talked when we drove around the section earlier on about hair follicles appearing like this. More superficially in the skin, but bear in mind that hairs have to grow from somewhere so they grow from deeper down in the dermis and this would be the base of a hair follicle here. Now we go up on higher power again and again just let you see again the epidermis on the outside with it's varying number of layers, depending on where we are in the body. A hair follicle in cross section here, and the collagen of the dermis, this supporting structure that is sitting underneath Here we have a different case now. This is a section of dog skin, and various things that I'm pointing out to you here. On the surface of the skin, there's been some hemorrhage, where this biopsy has been taken. Where this piece of skin has been taken, there's been some hemorrhage. So this red staining material here, these are red blood cells that are sitting on top of the skin here, and there are some more up around this area here and here. The epidermis again is being pointed out to you here in this case. Here's a hair follicle again here, this one's a little bit more dilated, and there's a bit of a remnant of a piece of hair in this one, it's not so discrete as the ones we were just looking at. And again we've got the dermal collagen and the supporting connective tissue that sitting underneath the epidermis just being pointed out to you here. In this case here, we're now looking at the skin from sheep and just for interest, Julia, again, we got the hair follicle here in the sheep's skin. This structure that's surrounding it, this a very nice picture of this, this is called a sebaceous gland. And sebaceous glands are normal structures that produce a substance called sebum. It helps to waterproof the coat and the hairs. And you can see nicely in this section that this sebaceous gland is emptying into this duct here. So that it can then actually produce the sebum that gets onto the skin and helps give the animal a nice waterproof coat. And in this final section here, again, we're pointing out the epidermis to you here. Again, it's a bit thicker in this particular section here. I also wanted to point out, in this section of skin that we're looking at here, it's a bit inflamed. This animal has an itchy skin, we have an itchy red kind of skin. And so what that means is that the individual blood capillaries become more obvious. So this arrow here is pointing out to you a small blood capillary with three or four individual red blood cells that you can actually see quite nicely sitting within that structure. Often in a section of skin we don't readily see at these capillaries. Because if the skin's not inflamed then they tend to be quite quiescent and they're not so easy to pick up. And the other point, you may be able to detect in this section that there's actually a lot more round and oval nuclear type structures around here. These are nuclei of inflammatory cells. Normally in the dermis, I mentioned before the skin is an immunological active cite so it's got cells in it ready to response if there's pathogens that need to be dealt with. But in the normal skin there shouldn't be this number of these nuclei dotted around. These are nuclei of lymphocytes and other types of inflammatory cells that are around in this area because this animal has an inflamed skin. So that's just a little bit of some extra resources and extra idea about what other sorts of things we can see in the skin.
