Direction of sliding and relative sliding velocities within trypsinized sperm axonemes of Gallus domesticus.

Trypsin digestion of demembranated fowl spermatozoa caused a longitudinal splitting of the distal part of the axoneme. The resulting strands, consisting of groups of doublet microtubules, formed left-handed helices. On the evidence of electron micrographs, the digestion had caused the loss of dynein arms from the outer row; it is assumed that the doublets remained linked together by dynein arms of the inner row. When such helices were mechanically detached from the proximal flagellum and reactivated with adenosine triphosphate, they lengthened in an orderly way by inter-doublet sliding. All the doublets of the axoneme could be reactivated and in all instances the direction of sliding was the same as that reported for the cilia of Tetrahymena. Within the groups of doublets the measured inter-doublet displacements were generally similar, suggesting that the rates of sliding had been equivalent. These findings are contrasted with the differential pattern of activation that is assumed to occur in vivo.