Renal pyramids (or
malpighian pyramids or
Malpighi's pyramids named after
Marcello Malpighi, a seventeenth-century anatomist) are cone-shaped
tissues of the
kidney. The
renal medulla is made up of 7 to 18 of these conical subdivisions (usually 7 in humans). The broad
base of each pyramid faces the
renal cortex, and its , or
papilla, points internally. 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.