This's an electron micrograph of glomerulus.The glomerulus is a tuft of small blood capillaries located within the Bowman's capsule of the kidney. The main function of the glomerulus is to filter plasma to produce glomerular filtrate, which passes down the length of the nephron tubule to form urine.The rate at which the glomerulus produces filtrate from plasma is known as the glomerular filteration rate (GFR).The glomerulus is one of the key structures that make up the nephron, the functional unit of kidney.