The Tail Movement of Bull Spermatozoa

Abstract

Detailed observations of the tail movement of non-rotating and rotating bull spermatozoa have been carried out. For rotating sperm a helical tail wave was found with a ratio of the amplitudes of the two perpendicular components of approximately 3 to 1. For both types of cells the variation of the amplitude and the phase shift of the wave as it travels from the proximal to the distal part are reported. Model calculations indicate that the stiffness of the tail originates in the fibrous sheath, which has a Young's modulus of 3 x 10(7) dynes/cm(2). Active contractile elements distributed continuously along the tail are found necessary to maintain the amplitude of the tail wave against damping by the fluid drag. If the longitudinal fibers are identified with the contractile elements the maximum tension to be developed by these fibers is 4 x 10(6) dynes/cm(2). The energy dissipated by the "active" part of the tail wave is at least approximately 70 percent of the total dissipation.

Passive hydrodynamic synchronization of two-dimensional swimming cells

“…In addition, some spermatozoa pass waves along their flagella which increase in amplitude from head to tail, leading to another type of front-back asymmetry. 30 In contrast, swimmers whose flagellar waveforms or body is asymmetric with respect to the horizontal axis experience viscous torques, and thus cannot swim straight. It is therefore natural for us to focus on waveforms which are symmetric about the horizontal axis, but not the vertical.…”

Flagellar ultrastructure suppresses buckling instabilities and enables mammalian sperm navigation in high-viscosity media

“…the structural and mechanical support to stabilize the long flagella observed in most mammalian spermatozoa [2,3,[5][6][7][8][9]. In particular, Lindemann [9] hypothesized that only a reinforced flagellum would be capable of harnessing the increased power from the larger number of molecular motors present in a long flagellum, which is especially relevant for motility within the highly viscous fluids of the mammalian female reproductive tract [10].…”

Atp-Induced Sliding of Microtubules in Bull Sperm Flagella

“…In order to produce motion in the more bulky mammalian sperm, it is generally assumed that the coarse fibers participate actively in the motile process although an inactive elastic role has also been suggested (7) . An inactive elastic role has also been proposed for the fibrous sheath (9) .…”