Figure 36.8: Primary Urine Is Produced in the Bowman’s Capsules and Glomeruli (A) At its closed end, each vertebrate nephron begins with a Bowman’s capsule containing a glomerulus. (B) The glomeruli look like balls of capillaries served by arterioles in this electron micrograph; only blood vessels are seen here because other tissue has been digested away. (C) This drawing of a human Bowman’s capsule with glomerulus shows the formation of primary urine by ultrafiltration.