 
<translate> Ka ba da wani rafi na sani sannan kuma amsar. Pyramids na koda (ko pyramids na malpighian ko pyramids na Malpighi mai suna bayan Marcello Malpighi, masanin ilimin karni na sha bakwai) sune ƙwayoyin koda masu siffa. A cikin mutane, ƙwayar koda tana da 10 zuwa 18 na waɗannan ƙananan rabuwa. Babban tushe na kowane dala yana fuskantar ƙwayar koda, kuma samansa, ko papilla, yana nuna ciki zuwa ƙashin ƙugu. Ginshiƙan sun bayyana tsiri-tsiri domin an kafa su ne ta madaidaiciyar layi ɗaya na nephrons da kuma tarawa. Tushen kowane dala ya samo asali ne a kan iyakar corticomedullary kuma saman ya ƙare a cikin papilla, wanda yake a cikin ƙaramin calyx, wanda aka yi shi da madaidaitan ɗakunan tarin fitsari.  Bisa ga wannan nassin, me ya sa gindi yake da layi-layi? <eng> Give some stream of consciousness and then the answer. 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. 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.

Based on this passage, why do renal pyramids have a striped appearance? 