This tissue is of mesodermal origin. During early stages of mesoderm development, segmentation genes and inductive signals from the dorsal ectoderm divide the mesoderm into regions of different fate. The progenitors of visceral muscles and gonadal mesoderm arise from segmentally repeated regions of even skipped (eve) expression, whereas somatic muscles and heart derive from sloppy paired (slp) expressing domains. These stripes of distinct mesodermal fates are further subdivided along the dorso-ventral axis by an inductive decapentaplegic (dpp) signal from the overlying ectoderm, which is required for the specification of visceral mesoderm, in the eve domain, and dorsal vessel, in the slp domain.

In parasegments 4 to 9, fat body progenitors can first be detected in the eve domain at stage 10 through their expression of serpent (srp). Later, two secondary clusters of fat body progenitors can be detected in the eve and the slp domain. In paragesements 10 to 12, the primary fat body cluster is missing, whereas in parasegment 13 additional fat body precursors are also located within the dorsalmost protion of the mesoderm. At the onset of germband retraction, fat body cells increase in number through cell division, leading to the loss of the fat bodies segmental appearance. It now lies between the somatic mesoderm and the midgut visceral mesoderm.

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