Regional and Functional Differentiation in the Insect Fact Body

Insect fat body historically has been considered a single tissue with multiple and diverse metabolic functions. Recent findings indicate that functionally distinct regions of fat body exist in some insects and that these regions often have unique morphologies. Regionally differentiated fat bodies in Lepidoptera have been associated with the segregation of synthetic and storage activities. The loss of biosynthetic capacity for storage proteins at the beginning of metamorphosis is the consequence of the histolysis of a larval specific histotype, whereas the histotype that accumulates storage proteins persists into the adult stage. In Diptera, functional histotypes are arranged along the anteriorposterior axis and between the larval and adult stages. Based on these models. we predict that the use of immunological and molecular probes will lead to the identification of regionally and functionally differentiated fat body histotypes in many insects.