Nebenkern
nebenkern
"A product of the fusion of the mitochondria during spermatogenesis. After the completion of meiosis the mitochondria of the spermatid collect along side the nucleus and fuse into two masses; these wrap around each other to produce the spherical Nebenkern. During flagellum elongation the Nebenkern unfolds and the two derivatives (major and minor mitochondrial derivatives) elongate down the axoneme."