ACQUISITION OF DIFFERENTIATIVE CAPACITY IN IMAGINAL WING DISKS OF DROSOPHILA-MELANOGASTER

The wing discs from larvae undergoing molt from 1st to 2nd instar are able to differentiate some parts of the adult wing when forced to undergo a premature metamorphosis. The 1st structures which differentiate are parts of the wing hinge and the wing blade. As development proceeds and older discs are forced through metamorphosis, the capacity to differentiate moves out both proximally and distally until gradually all of the derivatives of a mature wing disc are formed. Individual structures often differentiate from young discs in an incomplete form and pattern elements, such as bristles or sensilla, are added as older discs are tested.