Fig. 4. The effects of surgical manipulations on the initiation of ecdysis in larvae and pupae. Animals were injected with 200 pmol of ecdysis-triggering hormone (ETH) (at 0 min), and surgery was performed 20 min later (black arrow). Controls were not treated surgically. ShamBr had their head capsule punctured and forceps inserted into the head region. ShamLig had a ligature placed and tightened between the suboesophageal ganglion (SOG) and the thoracic ganglia (TG); the ligature was then removed. Major ganglia were eliminated as described in the Materials and methods. Decerebration, —Brain; removal of the brain and SOG, —Br/SOG; removal of the brain, SOG and thoracic ganglia, —Br-TG; removal of the terminal abdominal ganglion, —Terminal. Bars are mean times + S.E.M. Sample sizes are indicated in parentheses. Letters represent significant differences from controls within groups (P<0.001), as determined by analysis of variance using the Tukey test for differences (=0.05). Different letters denote significantly different values within a group (P<0.001).