title: Microtubules in the spermatids of stick insects.
abstract: Spermatids from two phasmid species were seen to possess an unusually large amount of microtubules along the nucleus and tail. Some of the microtubules have a loosely fitting sleeve for half a micron or more. During late stages in spermiogenesis the microtubules aggregate and form one or several "microtubular crystals" consisting of electron-lucid tubular elements with a diameter of about 360 A. The tail flagellum contains five kinds of microtubular structures, which all have a substructure of longitudinal protofilaments that is clearly visible after fixation in the presence of tannic acid. The so-called accessory tubules have 17 protofilaments that have the same appearance as that in ordinary, 13-unit microtubules, but are somewhat thicker than those. It is evident that the protofilaments in both the 17-unit and the 13-unit microtubules run parallel or nearly parallel to the long axis of the microtubules. It is of interest that both types of microtubules possess a prime number of protofilaments which may give the fagellum certain functional advantages.
authors.affiliation: Department of Ultrastructure Research, Wenner-Gren Institute, University of Stockholm, Sweden.
authors.forename: B A
authors.initials: BA
authors.lastname: Afzelius
mesh_terms: D000818:Animals; D005407:Flagella / Q000648:ultrastructure; D007313:Insecta / Q000033:anatomy & histology*; D008297:Male; D008854:Microscopy, Electron; D008870:Microtubules / Q000648:ultrastructure*; D013087:Spermatids / Q000648:ultrastructure*