What term describes the outer layer of an organ or structure?

The term that describes the outer layer of an organ or structure is "cortex." In anatomical terminology, the cortex refers specifically to the outer layer of tissues in organs such as the brain, kidneys, and adrenal glands. This layer typically serves a protective role and is involved in various functions depending on the specific organ it is associated with.

For example, in the kidney, the cortex contains the renal corpuscles and the proximal and distal convoluted tubules, which play key roles in filtering blood and forming urine. In the brain, the cerebral cortex is essential for higher-level functions such as sensory perception, cognition, and voluntary motor actions.

The other terms, while related to specific structures, refer to inner layers or different contexts. The medulla is typically the innermost part of an organ or structure. Stroma refers to the supportive tissue of an organ, which can include connective tissues, blood vessels, and immune cells. The dermis is specifically the inner layer of the skin, lying beneath the epidermis, and although it is an outer layer in terms of the skin's composition, the cortex more broadly applies to various organs.