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During spermatogenesis in Drosophila, a single gonial cell produces 64 spermatids, which remain interconnected by fusome, a spectrin-rich tubulo-vesicular organelle. As spermatids elongate, individual branchiets of fusomes within each spermatid are converted into cylindrical structures called elongation cones (EC), and they remain at the growing ends. The confocal section presented in this figure shows a part of an intact testis stained with anti-α-spectrin (green), RITC:phalloidin (red), and anti-α-tubulin (blue), and within that section a typical EC is visible. The article by Ghosh-Roy et al. (Molecular Biology of the Cell [2004] 15:2470-2483) showed that the EC is the likely place of axonemal sheath assembly. This is also evident in this picture. A thin layer of cortical F-actin (red) assembly of individual spermatids is visible just below the EC structure. Cytoplasmic dynein-dynactin complex regulates the EC morphogenesis and membrane deposition at the growing ends of spermatids and thus delimits the membranous boundary (called axonemal sheath) of individual sperms as they grow. —Anindya Ghosh-Roy and Krishanu Ray