2. PCT: The proximal convoluted tubule DCT: The distal convoluted tubule

5. B C A A: Parietal layer of Bowman’s capsule B: Visceral layer of Bowman’s capsule C: Macula densa cells

8. A A B C D C A: Collecting duct B: Thick portion of loop of Henle C: Thin portion of the loop of Henle D: Vasa recta capillaries

11. A B A: Transitional epithelium of the ureter. B: Muscularis layers

14. A B A: Transitional epithelium. B: Muscularis externa

17. A B A: Transitional epithelium. B: Corpus spongiosum