Fat body


Fat body is a highly dynamic insect tissue composed primarily of storage cells. It is distributed throughout the insect's internal body cavity; the haemocoel, in close proximity to the epidermis, digestive organs and ovaries. Its main functions are nutrient storage and metabolism, for which it is commonly compared to a combination of adipose tissue and liver in mammals. However, it may also serve a variety of other roles, such as: endocrine regulation, systemic immunity, vitellogenesis, and housing of microbial symbionts.
Its presence, structure, cellular composition, location, and functions vary widely among insects, even between different species of the same genus or between developmental stages of the same individual, with other specialized organs taking over some or all of its functions.

Functions

The fat body serves different roles including lipid storage and metabolism, endocrine regulation, and immunity.

Development

The fat body is of mesodermal origin and is normally composed of a network of thin sheets, ribbons or small nodules suspended in hemocoel by connective tissue and tracheae, so that most of its cells are in direct contact with hemolymph.

Other arthropods

The fat body has been best studied in insects nevertheless it has been identified in other arthropod phyla including Chelicerata, Crustaceans and all major classes of Myriapoda, although not all subtaxa.