Renal pyramids

Renal pyramids (or malpighian pyramids) are cone-shaped tissues of the kidney. The renal medulla is made up of 8 to 18 of these conical subdivisions. The broad base of each pyramid faces the renal cortex, and its apex, or papilla, points internally. The pyramids appear striped because they are formed by straight parallel segments of nephrons.

Additional images
The base of each pyramid originates at the corticomedullary border and the apex terminates in a papilla, which lies within a minor calyx.