Expression of fng^a.hs (using heat shock) during larval development at the time fng is known to function in wing development results in approximately 10% of the resulting flies having typical fng mutant phenotypes with no wings or with abnormal wing outgrowths. The phenotype increases with a more severe heat shock regime, but viability is reduced dramatically. Expression of fng^a.hs (using heat shock) in females results in abnormal phenotypes in the ovary. The earliest defect seen is a fusion of egg chambers as they fail to pinch off normally from the germarium, generating large egg chambers with too many nurse cells. 2-5% of egg chambers are fused. The large egg chambers ("compound egg chambers") derive from the fusion of two or more cysts (generally they are formed from 2 cysts, but occasionally from 3 or 4), and the nuclei in the anterior are often much smaller than those at the posterior region. Compound egg chambers with 2 oocytes, one at either end, with nurse cell in between, or with one oocyte at the posterior and the other in the middle of the egg chamber are seen. Females expressing fng^a.hs (using heat shock) also produce oocytes with an abnormal multi-layered organisation of follicle cells. These cells are most often found in two locations; at the posterior of the oocyte, where the follicle cell layer is often several cells deep at stage 8-9 (in contrast to the wild-type single cell layer) and in the anterior-dorsal follicle cells, which show multilayered organisation at stage 10. However, multiple layers of follicle cells are seen at several positions in the egg chambers, and some egg chambers degenerate. Disorganised follicle cell layers are also seen. Overproduction of dorsal appendage material in abnormal locations is also seen and eggs may be shortened.