Final answer:
The renal columns, which are extensions of the renal cortex, separate the renal pyramids and provide support for blood vessels and connective tissue.
Step-by-step explanation:
The structure found separating the renal pyramids is the renal columns. These are extensions of the renal cortex that radiate down through the renal medulla, providing separation between the pyramids. The renal columns contain blood vessels and connective tissue, and they also divide the kidney into lobes. These extensions not only support the kidney's structure but also facilitate the passage of blood vessels that enter and exit the renal cortex. The renal pyramids, along with the adjoining cortical region, constitute the lobes of the kidney.