Structure of the Renal Corpuscle

00:01 Here is a diagram explaining the structure of the renal corpuscle.

00:07 Focus on the yellow colored part of the renal corpuscle. That really is Bowman's capsule. It's a capsule wrapping around another structure I'll describe in a minute.

00:19 That Bowman's capsule has got a very thin squamous parietal epithelium. And it then becomes continuous on the left hand side with the beginnings of the tubule system, the proximal convoluted tubule. Bowman's space confined within that capsule is where the filtrate is going to go after filtration from the blood capillaries. Now focus on the right-hand side of the diagram and locate an efferent arteriole and an afferent arteriole. The afferent arteriole brings blood in and forms a tuft of capillaries, a very coiled series of capillaries called the glomerulus. And blood flows through that glomerulus and then out through the efferent exiting arteriole. But during development, those vessels embedded. They're pushed up against Bowman's capsule and became encapsulated by the Bowman's membrane, the Bowman's epithelium. So we now call that covering shown here in yellow as the visceral layer of Bowman's capsule. It's like having a balloon and you're sticking your fingers into the balloon. The outer part of the balloon is the parietal layer of Bowman's capsule. And the part of the balloon that's now around your fingers is the visceral layer. Now as you see, that visceral layer is very specialized. The cells aren't squamous. The cells are called podocytes and they are very important part of the filtration process. They're structurally very important for filtration, and I'll show you details of that in a moment. Before we leave this diagram, look across now to the right-hand side and you'll see a tubule, a distal tubule. If you recall from our diagram when the distal ascending tubule or segment travels up, it becomes convoluted. And it becomes convoluted next to the glomerulus.

02:44 And that's very important because that distal tubule, that convoluted part of the distal tubule is in very close approximation to the afferent arteriole, and also the efferent arteriole. And that forms a complex that I'll describe towards the end of the lecture. It's called the juxtaglomerular apparatus. So just remember that area on the diagram that I've just shown you for later on when I start describing the details. On the left-hand side is I repeated that diagram just to help you recall structures. On the right-hand side is a structure of the glomerulus. You can see Bowman's space and you can see very flat squamous cells lining the parietal layer of Bowman's space, and you can see podocytes that are on the external surface of the blood capillaries in the glomerulus. These podocytes are the visceral layer of Bowman's capsule.

03:56 You can see red blood cells inside the capillaries. You can see other nuclei besides the podocytes which tend to be on the outside.

04:05 Those other nuclei probably belong, or certainly, belong to endothelial cells, but also mesangial cells. Embedded in that glomerulus are cells called mesangial cells which support the structure of the glomerulus, support the close association of the endothelial cells of the capillaries with the podocytes. But those mesangial cells are also phagocytic, and they also tend to regulate the flow of the blood through these capillaries. Here now is a diagram explaining the filtration