Intercellular adhesivity and pupal morphogenesis inDrosophila melanogaster

Leg and wing imaginal discs of mature larvae ofDrosophila melanogaster when treated with 0.1% trypsin for 5-10 min underwent a change in shape that closely resembled normal pupal morphogenesis. Simultaneously, the cells of the disc epithelium changed in shape from tall columnar to cuboidal. Colcemid eliminated microtubules but was without effect on the shape of the imaginal discs or their cells. Tryptic digestion reduced non-junctional intercellular adhesivity but septate desmosomes and gap junctions remained intact.It is proposed that the structure of imaginal discs permits the packaging of the anlagen of the adult integument so that they can change shape and replace the larval structures in a brief period. Apparently most of the definitive form of the pupal leg is built into the disc and becomes visible within a few minutes as intercellular adhesivity is changed.