Pattern reconstruction by dissociated imaginal disk cells of Drosophila melanogaster

Abstract

The cuticular patterns of wing and leg appendages of adult Drosophila melanogaster are delineated. These patterns consist of specific arrangements of a few types of bristles, hairs, and sensilla. Recombination of dissociated cells of imaginal disks, marked by two different genotypes, enables us to analyze in the metamorphosed structures the determination of single cells to differentiate into adult cell types and their capacity to reconstruct adult patterns.

While combinations of single cells from complete wing disks resulted in chimeric reconstruction of adult wing patterns, cell combinations of fragments from different districts of a wing disk lead to a complete segregation of the components. Consequently, (a) the isolated cells posess a definite determination for regional qualities, at least, and (b) this determination manifests itself in the separation of cells which belong to different patterns or regions.

Leg patterns of first male, first female, second and third leg differ with respect to several characteristics. Combination of cells from one leg disk results in an autonomous differentiation of each bristle type. In combinates of cells from different leg disks, the characteristic cell types differentiate according to their origin. Thus, in mature leg disks, the major cell types are already determined at the level of individual cells.

In these combinates there is also chimeric pattern reconstruction by cells coming from identical patterns in the different leg pairs. On the other hand, cells corresponding to different patterns in each leg pair appear segregated in combinates. Thus, the determined cell possesses some kind of spatial information which characterizes it as a cell in a certain place in a given pattern.

Some mechanisms responsible for pattern reconstruction are discussed.