Final answer:
The microscopic structure in the kidney that produces urine is the Nephron, which includes a renal corpuscle comprised of the glomerulus and Bowman's capsule, and tubules that modify filtrate into urine.
Step-by-step explanation:
The microscopic structure in the kidney that produces urine is called a Nephron. Each nephron includes a renal corpuscle, which consists of a tuft of capillaries known as the glomerulus and an encompassing structure called the Bowman's capsule. The Bowman's capsule collects the filtrate, which then travels through the nephron's tubules—starting with the proximal convoluted tubule, then through the loop of Henle, and finally through the distal convoluted tubule—where it is modified into urine through the processes of filtration, absorption, and secretion. Forming urine refers to the transformation of this filtrate into the final urine that is excreted from the body.