Fig. 1. Time course of cyclic GMP immunoreactivity (cGMP-IR) in abdominal neurons during larval ecdysis after injection of ecdysis-triggering hormone (ETH). Animals were injected with 200 pmol of ETH. (A) The intensity of cGMP-IR was quantified, as described in Materials and methods, for 5-15 samples per time point. Standard error bars were generally small, but have been omitted for clarity. Blue lines represent immunoreactivity in cells 27 and 704. The orange line represents immunoreactivity in paired cells L_2,5. The green column represents the time of eclosion hormone (EH) release, based on Ewer and Truman (1997). The black arrow represents the mean time of the start of ecdysis (E). (B) Video micrographs show the cGMP response in neurons. Each photograph is a video montage of 2-3 optical sections to show neuron morphology optimally. Cells 27 and 704 are marked with a blue arrow, and the L_2,5 cells are marked with an orange arrow. Times of dissection (in minutes) are noted in the lower left-hand corners. Scale bar, 150 µm.