part of Nebenkern derivative major mitochondrial derivative Bigger mitochondrial derivative that develops from mid elongation spermatid stage onwards. It initially lies at a 90 degrees angle to a plane that splits the central pair of axoneme microtubules. This decreases gradually to 60 degrees during elongation, returning to 90 degrees during the later stages of spermatid differentiation. Late in the elongation stage, there is a deposition of a paracrystalline array of densely staining granules closely juxtaposed to the axonemal sheath. FBbt:00004952 fly_anatomy.ontology cell component male-specific anatomical entity