Expression of east^Scer\UAS.cWa under the control of Scer\GAL4^hs.PB (in the absence of heat shock) results in salivary glands which are dramatically reduced in length and diameter in third instar larvae compared to those in control larvae. The polytene nuclei of the salivary glands show high variability with respect to DNA content, diameter of the nuclear envelope and configuration of chromosomes and most of the nuclei have a wider spacing between chromosome strands than normal. Expression of east^Scer\UAS.cWa under the control of Scer\GAL4^ftz.ng does not affect the growth of the salivary glands. A small proportion of the salivary gland nuclei show increased spacing between chromosomes. Expression of east^Scer\UAS.cWa under the control of Scer\GAL4^{nos.UTR.T:Hsim\VP16} results in a distinct gap forming between a central chromatin mass and the nuclear envelope in male germ cells.