No immunostaining was apparent until the onset of spermatid elongation, at which time the early flagellar structures showed patchy but distinct staining. In invertebrates, kinesin-II has been implicated in intraflagellar transport and, therefore, in the process of flagellar assembly and maintenance. In addition, KIF3 family members, of which kinesin-II is one, are thought to be involved with transport of a subset of membrane-bounded vesicles in neurons. Although KIF3 occurs at high levels in testis, the specific antibody (clone K2.4) used by us to probe rat testis did not detectably react with any structures within Sertoli cells. flovent inhaler
Our data provide the first morphological evidence for the presence of kinesin-II in mammalian spermatid tails and for the intermediate chain of cytoplasmic dynein in Sertoli cell regions involved with spermatid transport. Results with the IC74 antibody are generally consistent with the microtubule-based model of spermatid translocation and indicate that at least one of the motor proteins involved in the process may be a cytoplasmic dynein. If involved, because microtubules are arranged with their plus ends at the base of the Sertoli cells, this motor would most likely be responsible for the apical movement of elongate spermatids that occurs just before sperm release.