ABSTRACT
A temperature sensitive lethal allele of the wingless locus of Drosophila melanogaster together with previously studied lethal and viable alleles in this locus, has been used to study some properties of this locus. These studies show the existence of two lethal phases for the wingless lesion; one during embryogenesis and another during pupation. By growing embryos with temperature sensitive wingless lesion at the permissive temperature and letting the larvae develop at non-permissive temperature, a large-scale cell death and subsequent regeneration were seen to occur in the mutant wing discs. This cell death followed by regeneration alters the normal developmental potential of the wing disc. Disc transplantation experiments show that these discs are incapable of differentiating into wing blade structures.