What layer of protection surrounds the kidney and is composed of adipose tissue?

The layer of protection surrounding the kidney that is composed of adipose tissue is known as perirenal fat. This layer of fat serves as an important anatomical structure that provides cushioning and helps to insulate the kidneys. It is situated between the renal capsule, which is a fibrous outer covering of the kidney, and the renal fascia, which is a connective tissue layer that further supports the kidneys.

Perirenal fat not only helps in protecting the kidneys from physical trauma but also plays a role in keeping them in place within the retroperitoneal space. This adipose tissue is critical for safeguarding the kidneys from potential friction against other abdominal organs.

In contrast, Gerota's fascia is a fibrous encasement around the kidneys and perirenal fat but does not consist of adipose tissue. The true capsule, also known as the renal capsule, is a dense connective tissue layer directly adhering to the surface of the kidney. Renal fascia is a connective tissue membrane that helps anchor the kidneys to surrounding structures. Thus, the best answer that specifically identifies the adipose tissue layer is indeed perirenal fat.