Dissection and Mounting of Fruit Fly Larval Brain Explants

Begin with the larvae of Drosophila, a fruit fly, in a physiological saline solution inside a dish. The solution prevents the larvae from dehydrating.

Under a dissection microscope, locate the anterior end of the larvae with the mouth hooks.

The anterior end contains the eye disks and the central nervous system, or CNS, which comprises the brain lobes and a ventral nerve cord.

Hold the posterior end of the larva using forceps. With another pair of forceps, pull the anterior end to extract the internal organs.

Remove the gut and attached muscles to isolate the CNS attached to the eye disks.

To mount the brain explant, transfer the extracted tissue onto the saline solution enclosed within a grease barrier on a glass slide.

Ensure that the dorsal side of the explant is facing up, and seal the tissue with a coverslip. The brain explant is ready for analysis.

To harvest brains from larval Drosophila, under a dissecting microscope, use one pair of number 5 standard-tip dissection forceps to hold a larval specimen in place, while using the other to carefully dissect out the brain, preserving the eye disks, brain lobes, and ventral nerve cord. Then, remove the attached muscles to minimize any movement of the sample during imaging. When all of the brains have been harvested, use vacuum grease to draw a square chamber onto a glass slide, and add 20 microliters of external saline solution to the chamber.

Use the forceps to transfer the brains to the chamber and adjust the positions of the brains under the microscope, with the dorsal sides facing up. Cover the chamber with a glass coverslip and press gently on the coverslip to reduce sample drifting during the imaging procedure.