Sometimes considered a specialized connective tissue rather than connective tissue proper, adipose is an exception to the general characteristics because its cells are closely packed and it has little matrix. The adipose cells store lipid in a large vacuole which fills each cell. Adipose is important for shock absorption and insulation and is found around many organs such as the heart, eyes, kidneys, spleen etc. as well as under the skin and in the medullary canal of long bones. Subcutaneous fat is a major stored fuel for aerobic activities. Adipose is also found associated with the serous membranes of the body.