Studies on the eel sperm flagellum. 2. The kinematics of normal motility

Abstract

The sperm flagellum of Anguilla anguilla lacks outer dynein arms, radial spokes and central structures. Its characteristic motion has been obtained by studying cells swimming perpendicularly against, but not adhering to, the coverslip. The flagellum generates a sinistrally helical wave of rising, then falling, amplitude. The frequency of the wave, which can exceed 70 Hz, is inversely related to its maximum amplitude. As a reaction to the torque, the entire cell rolls (spins) in the opposite direction to that taken by points on the flagellum in the generation of the sinistral wave. However, because the head (which contributes on opposing torque) is asymmetrical, the axis of this counter‐rotation is displaced laterally from the axis of the flagellar rotation. As a result, the flagellum precesses around the progression axis, with each point on the flagellum travelling along a special flagelloid curve, specified by the ratios of the two frequencies and the two radii for the circular motions. The instantaneous flagellar waveform (the flagelloid wave) is thus derived as a succession of phase‐shifted points on the series of flagelloid curves along the axis of the cell's rotation. This adds complexity to the underlying, rather simple, helical geometry. Calculations suggest that the forward swimming speed of the sperm is greatly aided by the orientation and shape of the sperm head. The movement of latex beads was observed around sperm swimming against the coverslip and around sperm swimming freely. Bulk, vortical flows of fluid were seen in the former case and net lateral displacements in the latter; this is in accordance with hydrodynamic theory for low Reynolds number systems. Cell Motil. Cytoskeleton 39:233–245, 1998. © 1998 Wiley‐Liss, Inc.

Studies on the eel sperm flagellum. 3. Vibratile motility and rotatory bending

“…In the work of Gibbons et al [1985] and in the preceeding paper in this series [Woolley, 1998] the motility of the 9 ϩ 0 eel sperm flagellum was described. Normal motility in this sperm flagellum was shown to be the generation of a travelling, sinistrally helical wave at frequencies that can exceed 70 Hz.…”

“…The strange orientation of the sperm head in these fish was interpreted as a coadaptation that increases the propulsive effect of the helical wave. Furthermore, the eccentric placement of the sperm head was shown to cause a systematic complication to the instantaneous flagellar waveform [Woolley, 1998].…”

Analysis of motility parameters from paddlefish and shovelnose sturgeon spermatozoa

“…Among fish with external fertilization, the traits of the motility behaviour of fish sperm flagella are quite similar in several respects Ishijima et al, 1998;Cosson et al, 1999). An exception is the eel spermatozoon, which can swim for very long periods with a beat frequency reaching 95 Hz, and with an original wave pattern, having a rolling motion at 19 Hz, with flagella developing a helicoidal three dimensional (3D) bending (Wooley, 1998). In the case of paddlefish and sturgeon, due to the rotation of the whole sperm cell, each spermatozoon image appears alternatively with flagellar top view (waves in the plane of observation) or side view (waves orthogonal to the observation plane); in addition, waves were also observed as 3D transiently during rotation of sperm cells (rotation frequency of 9-10 Hz, Table I).…”

Biophysics of Fish Sperm Flagellar Movement: Present Knowledge and Original Directions

“…An exception to wave's flatness can be found in European eel spermatozoa, which possess a corkscrew wave shape [7,19,103]. However, this helical wave pattern has lower efficiency in terms of forward velocity of the spermatozoa even though flagella beats at high frequency, up to 95 Hz [7,19].…”