Begin by pipetting around 400 microliters of dissection and imaging medium into each well of a three-well dissection dish. Working under a dissection microscope, wash the experimental larvae in dissection and imaging medium to remove food residues. While continuing to work under the dissection microscope, hold the larvae by the mouth hooks using one set of tweezers.
With another set of tweezers, carefully cut off approximately 1/3 of the larva from the posterior side. Next, while holding the larva by the mouth hooks using one set of tweezers, use the other set of tweezers to brush the cuticle towards the mouth hooks gently. Simultaneously, push inward with the tweezers holding the mouth hooks until the entire larva is turned inside out.
Invert the larva to expose the central nervous system and other tissues while maintaining their connection to the cuticle. Locate the central nervous system, or CNS, to avoid accidental removal. Gently remove non-CNS tissues using tweezers, keeping only the CNS and brain attached to the cuticle.
To release the brain from the cuticle by severing the axonal connections, using microdissection scissors, cut gently beneath the brain lobes. Then, cut the connections under the ventral nerve cord. Dissect larvae in batches to keep the dissection time under 20 minutes.
Transfer the dissected brain into a well containing the dissection and imaging medium. For imaging lasting over three hours, supplement the medium with fat bodies.
