why do renal pyramids have a striped appearance
Renal pyramids Renal pyramids (or malpighian pyramids or Malpighi's pyramids named after Marcello Malpighi, a seventeenth-century anatomist) are cone-shaped tissues of the kidney. In humans, the renal medulla is made up of 10 to 18 of these conical subdivisions.[1] The broad base of each pyramid faces the renal cortex, and its apex, or papilla, points internally towards the pelvis. The pyramids appear striped because they are formed by straight parallel segments of nephrons and collecting ducts. The base of each pyramid originates at the corticomedullary border and the apex terminates in a papilla, which lies within a minor calyx, made of parallel bundles of urine collecting tubules.
Ureter In human anatomy, the ureters are tubes made of smooth muscle fibers that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually 25–30 cm (10–12 in) long and around 3–4 mm (0.12–0.16 in) in diameter. Histologically, the ureter is lined by the urothelium, a type of transitional epithelium, and has an additional smooth muscle layer in the more distal one-third to assist with peristalsis.