 All right, let's talk about some prostate anatomy with these elegant series of diagrams. And we're going to layer on different portions of the gland as we move forward. So we started out here in yellow with the urethra. And we'll break the urethra down later on into its individual subsegments and show you the urogenital diaphragm, which would be here. So in your mind's eye, this would be inferior or caudal, and this would be superior or cranial. So the urethra is yellow. We've got the expanded virumontanum. And then the urethra continues on up into the bladder. We've also got these two purple structures, the ductus deference, which leads to the seminal vesicles. And the seminal vesicles will be located posturose superior to the prostate gland. They're secreting organs, so they contain secretory material, although after ejaculation they will empty. So some people suggest that you not do prostate MRI within one week after ejaculation. That's a lot to ask. However, as you get older, these may desiccate or dry out and have less secretory material inside them. So there's a lot of variability regarding the signal in these glands, as we'll see later. And that could be a potential pitfall and source of confusion. Now let's move on to another section, the transitional zone. And the transitional zone is part of the central gland. So this is a little bit confusing. Let's really kind of drill down into this with a little more granularity. The central gland consists of the central zone and the transitional zone together. So often, we don't make a distinction between the two. We'll often just call disease in these locations, within the central gland, the central zone. Even though the central gland is composed of two components, the transitional zone and one that's located more posterior and superior, the central zone. The central zone can be pretty big, varies in size. And both of these will increase in size with advancing age. And in fact, they can get so big that they can push out on the remainder of the anatomy of the gland and in some ways obscure the peripheral aspect of the gland. Now the peripheral aspect of the gland is extremely important, because that's where 70% of all the cancers occur. They're easier to identify in this region as we'll see later on. And the criteria for identifying disease in the central gland, which consists of the central zone and transitional zone, a bit tougher. Let's keep going, shall we? The next layer that we're going to put in is the peripheral zone. And it's kind of like an envelope. Now, notice that the peripheral zone has a very distal apical component. So tumors that exist around here can have not only a big impact on the urethra, but they can also be hard to reach, hard to see, a little more challenging to biopsy. This envelope goes all the way around the right side and the left side of the central gland. It'll scoop around back of the central gland, and you're going to get a much better appreciation for this when we look at it with cross-sectional anatomy. And I think this three-dimensional anatomic diagram does it justice. The next section is the anterior fibromuscular stroma, which is fairly symmetric. It's thin, it's on the right and left side of the gland, and it's anterior. It has a fairly long apical extension, inferiorly. And because prostate carcinoma is dark, and the fibromuscular stroma is dark, this is where the diffusion-weighted image is really important and really shines. Because the cancer will diffusion restrict, and the anterior fibromuscular stroma will not restrict. Not only is it anterior, it's composed of fibrous tissue, and fibrous tissue is dark, cancer is dark. So this could be a little bit of a conundrum and a potential pitfall if you don't pay attention to the diffusion-weighted image. Fibromuscular stroma in the anterior portion of the gland, somewhat pan-caped shaped and relatively symmetric from side to side.