Intercalary regeneration in imaginal wing disk of Drosophila melanogaster

Abstract

IN this paper we show for the first time that the developmental capacity of imaginal disk cells from Drosophila can be altered by appropriate grafting operations. The appendages of amphibians and immature arthropods, and the imaginal disks of holometabolous insects, are capable of undergoing pattern regulation when parts are removed. (Pattern regulation is used here to describe the alteration of cell fates in response to an abnormal situation in a developing system; we include under this term both regeneration and duplication.) Regulation then occurs during growth of the tissue by cell division, a process termed epimorphosis¹. A characteristic feature of epimorphic regulation which has recently been recognised, is the different regulative responses shown by complementary pieces. For example when an imaginal disk of Drosophila is bisected and allowed to grow for some time, one of the two fragments usually regenerates the missing parts, while the other undergoes duplication of the presumptive pattern already present². Similarly, whereas the stump of an amputated amphibian or cockroach limb can regenerate distally, the amputated distal part, if kept alive by grafting to a host animal, can also undergo pattern regulation by forming the distal pattern elements, thereby duplicating itself^3–6.