 We have five flavors of leukocytes that we're going to talk about. And you're going to remember your leukocytes and how abundant they are based on this not very nice mnemonic device. I'm not going to write down the words of the mnemonic device, but I'm going to tell you what it is. Never let monkeys eat bananas. They're very nice because, I mean, monkeys probably really like bananas and so it seems kind of cold-blooded to say no bananas. No bananas for you, poor little guys. But if you remember, never let monkeys eat bananas, then you have got your white blood cells all knocked out. So let's write down who they are. We have neutrophils. They are the most common. Let's see if we're going to have a problem, neutrophil, no problems. We have lymphocytes. Second, in fact, let's do our abundance numbers right now. Neutrophils are about 50 to 70% of all white blood cells. That seems like a lot. That's what it is. That's crazy. That's a lot. So when you're looking at a blood slide, most of the white blood cells that you're going to see are going to be neutrophils. This is abundance not of all cells. This is just of white blood cells because what we know is that there's a jillion red blood cells for every one white blood cell. Lymphocytes, there are between 20% to 40% of your white blood cells are lymphocytes. We have between 2% and 8% of our white blood cells are monocytes. Eocinophils, between 1% and 4% of your white blood cells are eocinophils. That's the eating part of the Never Let Your Monkeys Eat Bananas. And then we have basophils. And basophils are less than 1% of your white blood cells. So tell me, when we're doing our Easter Egg Hunt, our scavenger hunt for white blood cells in lab, who are you going to have the hardest time finding? The basophils are definitely going to be the most challenging. So let's fill in this chart for the neutrophils first. So I'm going to start out with their function because, you know, that's the first thing on the list. The function of the neutrophils is primarily phagocytosis. And in Wendyland, that is yumpsilization. These guys are roaming around and yumpsilizing bacteria, mostly bacteria. That's who they mostly are getting rid of. They don't live very long though. That's the story. They live between one and two days. So they roam the blood. They're floating around in the blood. There's lots of them, relatively speaking. And they're just yumpsilizing bacteria everywhere they go. They also, they have granules in their cytoplasm. And I'm going to show you that in a second. But something that you'll notice that end with fill are filled with granules in the cytoplasm. And think of granules as like Kool-Aid, Kool-Aid powder, where when they're inside the cytoplasm, they're like Kool-Aid powder. And then you can dump that Kool-Aid powder out into the blood and that now you've got all these chemicals out into the blood that can go do something. Well, the neutrophils, one of the things that their neutrophils can do is, I mean, one of the things that their granules can do is cause fever. And so the granules consist of a special chemical called a pyrogen, which causes fever. It's kind of interesting. Okay, so what do they look like? Well, since you asked, they look like that. They have a distinct nucleus and the nucleus is multi-lobed. And while my little image is going to be like, oh, yeah, it looks like that. They're not all going to look like that. But you will see this multi-lobed nucleus. So let's go look. Back to my favorite site ever, which is the University of Michigan Histology website. Can you see my blood? Look at all. This is what we're going to look at in lab today. Look at all the red blood cells. Holy, yeah, there's a trillion of them. These big purple circles, these are my white blood cells. If you notice, do you see how this one and this one looks different? And these three look a little more like each other than they look like this one. In fact, oops, I kind of want to go down here. Like those guys look even different than these guys. Okay, let's just go in and look at them. Look at my multi-lobed nucleus. Neutrophils are filled with granules. And you can kind of, in this vision, you can kind of like, dude, I see granules in there. Most of the time, you can't see your granules. You're going to identify your neutrophils in your nucleus and at least compared to our other fills, the number of granules in there is really, really small. While we're here, take a look at the garbage next to the red blood cells. There's garbage in this side. There's like dirt in this side. Those are your platelets. You can actually identify your platelets in your blood slide. All right, so we've got our neutrophils. You have a sense of those guys. Let's talk about lymphocytes. Okay, I want to talk about lymphocytes next because they're the next most abundant. But we're going to talk about eosinophils next, so we're not going to fill these out in order. And if you think about it, go ahead and try and guess why I'm doing that because I almost forgot why I was doing that. I'll be right back.