Remember, the nephron contains a portal system, two capillary networks. The glomerolus is the first capillary network and the base erectecta is the second capillary network. So let's take a look at our glomerulus. So the glomerulus consists of two types of specialized cells. So lining the capillaries of the glomerulus are cells known as endothelial cells. And endothelial cells are basically involved in filtration.