The correct regulation of organ size is a fundamental developmental process, the failure of which can compromise organ function and organismal integrity. Consequently, the mechanisms that regulate organ size have been subject to intense research. This research has highlighted four classes of mechanism that are involved in organ size regulation: physiology, plasticity, patterning and physical force. Nevertheless, how these mechanisms are integrated and converge on the cellular process that regulate organ growth is unknown. One group of animals where this integration is beginning to be achieved is in the insects. Here, I review the different mechanisms that regulate organ size in insects, and describe our current understanding of how these mechanisms interact. The genes and hormones involved are remarkably conserved in all animals, so these studies in insects provide a precedent for future research on organ size regulation in mammals.
Keywords: adhesion; hormone; hypoplasia; imaginal disc; insect; insulin; morphogens; size regulation.