emc^as.hs animals heat shocked as embryos 2 or 4 days after egg laying have a high penetrance of duplicated or truncated thoracic bristle phenotypes as adults. These phenotypes are seen at low penetrance (<10%) if heat shock treatment is given on days 3, 6 or 7 after egg laying.

The ovaries of heat shocked emc^as.hs adult females contain fused egg chambers. Sometimes these a full double egg chambers (with 32 germ cells) but often they are partial fusions of 2 egg chambers resulting in one abnormally large egg chamber with >16 germ cells and one small one with <16. These egg chambers often appear apoptotic, although development proceeds to at least stage 11 in some cases. The eggs laid by these flies show varying degress of ventralisation - from dorsal appendages positioned closer together, through partially to full fusion of dorsal appendages. Non-fused dorsal appendages are often broader, shorter and misshapen and often have split-ends.