Fig. 2. Primary cultures derived from Drosophila embryonic cells contain a mixture of different cell populations that include muscles and neurons.

(A-D) Primary myotubes strongly stained by phalloidin (A, red in the merged image in D) are all stained for Mhc (B, green in the merged image in D). Note that other cell types whose nuclei are revealed by DAPI (C) are faintly visible by phalloidin staining. As myotubes mature they become more contractile, some detach from the tissue culture surface, and are seen as round muscles (arrows in A,B,D). (E-H) Primary cells were isolated from Dmef2-Gal4, D42-Gal4, UAS-mito-GFP embryos in which Dmef2-Gal4 and D42-Gal4 drive expression of mito-GFP, a mitochondrial marker transgene that fuses the mitochondrial targeting signal to the N-terminus of EGFP, in muscles and motoneurons, respectively. Muscle structure is visualized by phalloidin staining of Actin (E, red in the merged image in H), and neurons can be seen in F (green in the merged image in H) as they stain strongly with mito-GFP but not phalloidin (triangles in F,H). In addition to neurons and muscles, other cells are present in the culture, as revealed by the staining with DAPI (G, blue in the merged image in H). In H, muscles are shown in red and yellow, neurons and their extensions in green only. Scale bar: 50 μm.