The overall goal of this procedure is to study muscle-tendon morphogenesis in living Drosophila pupae.This method can help answer key questions in the muscle development field.Such as how muscle cells interact with their tendon targets, and when they acquire the ability to twitch.The main advantage of this method is that muscle-tendon morphogenesis can be studied in the intact organism, and over many hours.To begin the protocol, use a wet brush to collect white pre-pupae from the walls of the bottles of fly stocks, and transfer them to a glass slide.Next, under a stereo microscope, remove clumps of fly food sticking to the pupae with a wet brush, and orient the ventral side of the pupae towards the glass slide.Discard the pupae that have started to turn brown, or that are still moving.Label the glass slide with the genotype, date and time of collection.Transfer the slide to a Petri dish and add a wet tissue to prevent the pupae from drying out.Store the pupae in an incubator at 25