Also found in: Dictionary, Medical, Wikipedia.
fat body[′fat ‚bäd·ē]
(1) Areolar tissue in the body of insects and some other arthropods that fills the spaces between the internal organs and underlying walls of the body. The cells of the fat body are rich in fat (hence the name). It is filled with tracheae and may be white, orange, yellow, or green. The cells of the fat body are the site where nutrients (fats, proteins, and carbohydrates) accumulate and where metabolic products (uric acid salts and so forth) accumulate and are excreted. In larvae, the fat body consists of external (parietal) and internal (visceral) lobes. This division is indistinct in adult insects.
In some luminescing insects, the fat body or a separate organ contains a luminescing substance called luciferin. In many insects, the fat body contains the so-called mycetomes—symbiontic microorganisms (bacteria, fungi) that participate in metabolism and are found in certain parts of the fat body.
(2) In amphibians, the fat body is a yellow irregularly shaped structure located above each testis that nourishes the testis and the spermatozoa developing in it.