The mass of the renal medulla is primarily made up of two structures: the renal pyramids and the renal columns.
The renal pyramids are cone-shaped tissues that are organized in a radial array within the medulla. Each pyramid contains the nephron loops and collecting ducts that process and transport urine. The apex of each pyramid opens into a minor calyx, where urine is collected before moving to the renal pelvis.
On the other hand, the renal columns are the extensions of cortical tissue that separate the renal pyramids. They are composed of blood vessels, nephrons, and interstitial tissue. These structures are vital as they support the pyramids and contain renal cortex materials.
Together, the renal pyramids and columns play a crucial role in the kidney’s ability to filter blood and form urine, thus making them essential for renal function.