Fat Body

Ephraim Cohen

The Hebrew University of Jerusalem

The insect fat body is a mesodermal tissue composed of a meshwork of loose lobes suspended in the hemocoel and bathed in the insect hemolymph. The tissue is composed primarily of vacuolated rounded or polyhedral cells called adipocytes or trophocytes, which commonly harbor stored inclusions of proteins, lipids, and glycogen. In certain insect species, mycetocytes (cells containing symbiontic microorganisms) and urocytes (cells containing nitrogenous waste product in the form of uric acid) are present. The fat body is also associated with connective tissue and various blood cell types. Being a major biosynthetic and storage organ in insects, the insect fat body is equivalent to the vertebrate liver. It is the prime location of intermediary metabolism and detoxification processes, as well as storage and excretion of glycogen, lipids, and proteins. Storage of reserves is characteristic of the larval fat body cells. Such reserves are subsequently used for metamorphosis in holometabolous insects and for flight and reproduction in adults.

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