Cylindrical organelles associated with microtubules during sperm elongation in a mealybug.
Spermiogenesis in the mealybug Pseudococcus obscurus involves the elongation of a cytoplasmic papilla from the surface of a spermatid. Longitudinally oriented fibers and microtubules, with diameters of 250 A and a non-9+2 arrangement, are associated with this process. Fibers alone are found in early stages of papilla emergence and in the basal region of the elongated papilla. They appear to be continuous with the microtubules in the more distal region of an elongated papilla. Disk-shaped, circular, and rectangular profiles are associated with the basal ends of the fibers. Probably the fibers are microtubular "anlagen" and the associated structures may be microtubular "organizing centers".
D000818:Animals; D007313:Insecta / Q000502:physiology / Q000648:ultrastructure*; D008297:Male; D008870:Microtubules / Q000648:ultrastructure; D013091:Spermatogenesis; D013094:Spermatozoa / Q000648:ultrastructure*