Fig. 2. Primary culture of isolated cyst from Drosophila testis. (A) DIC image of dissected testis. Large arrowhead indicates basal (seminal vesicle) end of testis. Fibers (arrows) are elongated cysts. At the apical end (small arrowhead), a number of round cells are seen which are spermatocytes and spermatids at early stages. (B) Isolated individualizing cyst. Large white arrowhead indicates a moving cystic bulge. Large arrow indicates the direction of movement. The cystic bulge starts from the end with sperm nuclei (small white arrowhead) and moves to the apical end (end of sperm tail, small arrow). Small black arrowhead indicates the nuclei of somatic cyst cells, which surround the cyst. (C-F) Cystic bulge at various stages of individualization. The arrow at the bottom indicates the direction of movement of the cystic bulge. (C) Early cystic bulge right after onset of movement (arrow). (D) Cystic bulge in the middle of cyst. (E) Cystic bulge at tail end of cyst. Round waste bag can be seen (arrow). (F) Individualizing spermatids with cyst cells removed. The individualized region of a number of thin sperm tails (small arrowheads) are visible adjacent to the cystic bulge (arrow). (G) An isolated cyst undergoing individualization from head to tail. (H) Representative plot of movement of the cystic bulge. Scale bars: 100 µm in A,B; in F, 50 µm for C-F.