In this video, we're going to begin our lesson on granulocytes, which are cells of the innate immune system. And so these granulocytes are white blood cells or leukocytes with visible cytoplasmic granules, which is really implied by their name. You can see the granules within their name. And so these granules are cell structures that contain compounds that are used for protective functions and are visible under a light microscope. Now, there are 3 main types of granulocytes that are named based on the staining properties of their granules.
The first main type of granulocyte are the neutrophils, and the neutrophils actually have a nucleus with 5 lobes. So, they have a 5-lobed nucleus, and they have really small granules which do not stain very well. And so, their granules remain somewhat of a neutral color, which is why they're referred to as neutrophils. Neutrophils are also sometimes referred to as polymorphonuclear neutrophils, because poly is a root that means many, and morphonuclear is talking about a morphed nucleus. And so, these are abbreviated as PMNs.
If we take a look at our image below, notice over here on the left-hand side, we're showing you the granulocytes and notice that we're showing you the neutrophils on the far left. And notice that they have a 5-lobed nucleus, and their granules are so small that they don't stain very well.
The next type of granulocyte that we have here are the eosinophils. And the eosinophils have 2 to 3 lobes in their nucleus, and they have larger granules that stain a reddish-orange color. If we take a look at our image below at the eosinophils, notice that their nuclei have 2 to 3 lobes and they have these larger granules that stain a reddish color.
The last type of granulocyte is going to be the basophils. And the basophils have a 2-lobed nucleus, and they have larger granules that stain a darker blue, or purple color. If we take a look at the basophils below, notice they have a nucleus with 2 lobes and they have these larger granules that stain a purplish-blue color.
As we move forward in our course, we'll be able to talk a bit more in detail about each of these different types of granulocytes: the neutrophils, eosinophils, and basophils. And so, this here concludes our brief introduction to the granulocytes. Once again, we'll be able to learn more about them as we move forward. So, I'll see you all in our next video.