 
<translate> Nye ụfọdụ iyi nke nsụhọ na mgbe ahụ azịza ya. Renal pyramids (ma ọ bụ pyramids malpighian ma ọ bụ pyramids Malpighi aha ya bụ Marcello Malpighi, onye na-ahụ maka ihe ndị dị na narị afọ nke iri na asaa) bụ anụ ahụ dị ka cone nke akụrụ. N'ebe ụmụ mmadụ nọ, akwara akwara mejupụtara 10 ruo 18 n'ime nkebi ndị a yiri cones. Ntọala sara mbara nke pyramid nke ọ bụla na-eche ihu n'akụkụ akụrụ, elu ya, ma ọ bụ papilla, na-atụkwa n'ime n'akụkụ pelvis. A na-ahụ pyramid ndị ahụ dị ka hà nwere ahịhịa n'ihi na ha bụ akụkụ nke nephrons na ọwa mmiri ndị na-achịkọta ihe ndị dị n'ahụ́ bụ́ ndị dị n'akụkụ ibe ha. Ntọala nke pyramid nke ọ bụla na-amalite na oke corticomedullary na elu ya na-ejedebe na papilla, nke dị n'ime obere calyx, nke e mere site na ụyọkọ nke tubulus na-anakọta mmamịrị.  N'ihi ihe e kwuru n'ebe a, gịnị mere pyramid ndị dị n'akụrụ ji enwe ahịhịa ndị na-ese n'ahịrị? <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? 