Eggs from Dmn^hs.PD females heat shocked for 1 hour have dorsal patterning defects of varying severity. In milder cases the dorsal appendages are positioned correctly along the anterior-posterior axis, but are fused at the base or along their entire length. In more severe cases the dorsal appendages are highly reduced or absent, and their rudiments are displaced posteriorly. The highest frequency of dorsal appendage defects occurs in eggs collected 20-25 hours post heat-shock (45%) and 25-30 hours after heat shock (33%), approximately corresponding to heat shock at stage 8-9 of oogenesis. However, the proportion showing posterior displacement of dorsal appendage rudiments never exceeds 5%. The incidence of dorsal appendage fusion is significantly increased in flies carrying 4 copies of Dmn^hs.PD heat shocked for 30 minutes 5 times over a 5 hour period, but there is no increase in the numbers of eggs with posteriorly displaced dorsal appendages. 12 hours after a 1 hour heat shock, a small but significant proportion of stage 9 Dmn^hs.PD oocytes (4-9%) have a severely mis-positioned nucleus. In these cases the nucleus may remain associated with the cortex, or detach completely from it: about half of misplaced nuclei are clearly separated from the cortical layer of microfilaments.