So here we have an example problem that says to label the indicated areas of the thymus micrograph. And of course, recall from our previous lesson videos that the thymus is a bilobed organ, meaning it has two lobes. And here in this micrograph, we're showing you just one of the lobes. Each of the lobes of the thymus is made up of a bunch of smaller individual lobules. Notice that this bracket over here is labeling one of these lobules, so we can go ahead and label it as so. However, the lobules are found all throughout the lobe.
Now, each of these lobules is going to have an inner region that is in a lighter purple color here in this micrograph that we call the medulla. Also, each of these lobules has an outer region that in this micrograph is in a darker purple color, and we call this the cortex. Recall that the immature T cells that are migrating from the red bone marrow arrive on scene at the thymus in the outer cortex. And as those immature T cells are developing and maturing, they migrate toward the inner medulla. The inner medulla has the matured T cells.
Surrounding or encapsulating the entire lobule is a layer of dense irregular connective tissue that we call the capsule. The inward invaginations or the inward extensions of the capsule that separate out the lobules from each other are called the trabeculae, which are also known as the septa, or singular would be septum.
This here concludes this example problem, and I'll see you all in our next video.