Final answer:
The layer below the renal fascia and over the renal capsule is the adipose tissue, also known as the renal fat pad. It provides cushioning to the kidneys within the three external layers that protect them. The layer supports the kidneys along with the outermost renal fascia and the fibrous innermost renal capsule.
Step-by-step explanation:
The layer that covers the renal capsule and is located below the renal fascia is the adipose tissue. This layer is commonly referred to as the renal fat pad or the perirenal fat capsule. Externally, there are three layers surrounding the kidneys. The outermost is the renal fascia, an anchoring layer made of connective tissue. Directly under this lies the renal fat pad which consists of adipose tissue, providing protective cushioning to the kidney. The innermost of these three external layers is the renal capsule, a tough fibrous layer. Internally, the kidney is composed further of three regions: the outer cortex, a medulla in the middle, and the innermost region being the renal pelvis.
Regarding the structure of tissue, while areolar tissue, adipose tissue, dense regular connective tissue, and dense irregular connective tissue are all types of connective tissue, embryonic tissue is not considered a mature tissue type alongside muscle, nervous, and epithelial tissues.