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D. F. KATZ and H. M. DOTT

Summary.

Three basic approaches for determining the mean swimming speed of a suspension of microorganisms were compared, using bull and ram spermatozoa. Number fluctuation counting was performed automatically on a Quantimet 720 image analysing computer, the mean speed being obtained using 'probability after' statistics. The other two approaches were photomicrographic: number flux counting was performed on single photomicrographs; on the same photomicrographs, the mean speed was estimated from measurement of 'whole' and 'half' track lengths. These results were compared with each other and with the Quantimet results. The 'probability after' method was also compared, on additional samples, with cine-photomicrographic tracking. The mean speeds predicted by the 'probability after' method compared favourably with the other methods (range 68 μm/sec to 162 μm/sec). The results also suggested that, on single photomicrographs, measurement of 'half' track lengths or number flux counting were generally preferable to measurement of whole track lengths.

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D. F. Katz, J. W. Overstreet and F. W. Hanson

Summary. Movement characteristics of the seminal spermatozoa of 9 men of contemporary fertility were studied using time-exposure photomicrography. Five different ejaculates, collected over a 9-month period, were analysed for each man. The assessment of sperm motility focussed on classical parameters (% motile spermatozoa and the total swimming speed, considering all motile spermatozoa) as well as several newly defined movement characteristics (% progressive spermatozoa, progressive swimming speed, and % straight-swimming, rolling and yawing spermatozoa). These new measures distinguished weakly motile from vigorously motile spermatozoa, and also assessed geometrical attributes of the swimming trajectories of the vigorous spermatozoa. The % motility and the total and progressive swimming speeds did not differ significantly amongst the fertile men. The percentage of progressive spermatozoa differed significantly among the 9 men, but this was due to the outlying values of a single donor. Significant differences among men did occur in the percentages of straight-swimming, rolling and yawing spermatozoa. In addition, considerable variability was found among the different ejaculates of individual men.

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D. F. Katz, R. Yanagimachi and R. D. Dresdner

Summary. Spermatozoa were collected from the cauda epididymidis of golden hamsters and guinea-pigs, and the acrosome reaction was induced in vitro. Movement characteristics of the spermatozoa were assessed with high-speed cinemicrography. Before the initiation of the acrosome reaction (preactivated spermatozoa), sperm movement in both species was characterized by progressive swimming by regular flagellar waves of moderate amplitude and relatively high frequency. After the acrosome reaction (activated spermatozoa), sperm movement in both species was not progressive, and was characterized by whiplash-like flagellar undulations of significantly (P < 0·05) higher amplitude and lower frequency. Calculation of the hydrodynamic power output by a new theory indicated that no significant change occurred after activation.

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D. F. Katz, R. N. Mills and T. R. Pritchett

Summary. Movement characteristics of freely swimming spermatozoa were studied with high-speed cinemicrography. At 21°C, flagellar beat frequency was higher in midcycle human cervical mucus than in native semen or Tyrode's solution; the beat shape differed, possessing diminished amplitude and wavelength. Although the spermatozoa swam straighter in the mucus, the progressive swimming speeds did not differ in the three media. Swimming speed and beat frequency were linearly related in semen and in Tyrode, but in mucus the linearity was less certain. In midcycle cervical mucus at 37°C, beat frequencies and swimming speeds were greater than at 21°C, but the trajectories were equally straight, and the distances swum per beat (kinetic efficiencies) did not differ.

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L. J. Burkman, J. W. Overstreet and D. F. Katz

Summary. Spermatozoa were recovered from the isthmus of the rabbit oviduct at 4 and 11 h post coitum using several defined flushing media. The motility of spermatozoa in the isthmic flushings was subsequently analysed from video recordings. There was little sperm movement in the native isthmic fluid, but vigorous flagellar activity and hyperactivated movement were induced by flushing the isthmus with 0·25 m-sucrose, apparently an effect of dilution. Flushing with a complex culture medium resulted in similar stimulation of sperm movement.

When pyruvate was present in the medium, hyperactivated flagellar bending was stimulated, whereas these movements were virtually absent when glucose alone was present. The stimulating effect of dilution was less pronounced when the flushing medium contained 50 mm-potassium. When the isthmus was flushed with media containing 50 mm-K+ and the K+ concentration was lowered to 5 mm during a washing procedure, large-amplitude flagellar movements were sequentially suppressed and restored. The restoration of large-amplitude movements was enhanced when pyruvate was present in the 5 mm-K+ washing medium. These results suggest that alterations in the concentration of both K+ and pyruvate may have a role in regulating the motility of rabbit spermatozoa in the oviducal isthmus, K+ being inhibitory and pyruvate stimulatory.

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P. Morales, J. W. Overstreet and D. F. Katz

Summary. Spermatozoa from 10 fertile donors and from 10 patients with infertile marriages were washed and centrifuged (time zero, TO), and incubated in vitro in capacitation media for 6 h (T6), or 24 h (T24). At each time individual spermatozoa were classified as being morphologically normal or abnormal, and their movement characteristics were determined using high-speed videomicrography. Zona-free hamster oocytes were added to the T24 sperm suspensions. At all times, morphologically normal spermatozoa from donors and patients swam faster and had greater rolling frequency, flagellar beat frequency and amplitude than did abnormally shaped cells. Morphologically normal spermatozoa from donors exhibited a significant change in their movement pattern at T6. This change, which resembles hyperactivation in other species, was characterized by higher values of amplitude of lateral head displacement, and lower values of linearity, beat frequency and flagellar curvature ratio. In contrast, normal spermatozoa from patients showed only a decrease in straight line velocity at T6, with no other significant changes in movement characteristics. No changes in sperm movement could be demonstrated for the abnormal cells in either group of subjects. In sperm suspensions from donors and patients examined at T24, sperm vigour declined regardless of the morphological type. Spermatozoa from all 10 donors were able to penetrate the zona-free hamster oocytes, but spermatozoa from 5 of the 10 patients failed to penetrate oocytes. Correlations between hamster oocyte penetration and indicators of sperm vigour were demonstrated only for spermatozoa of patients.

Keywords: capacitation; sperm motility; hyperactivation; male fertility; sperm penetration assay

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D. F. Katz, B. T. Brofeldt, J. W. Overstreet and F. W. Hanson

Summary. Movement characteristics of 'vanguard' and 'following' human spermatozoa within cervical mucus were measured using high-speed cinemicrography. The data were applied to a mathematical model of the hydrodynamics of sperm–mucus interaction, using the methods of analysis of covariance and stepwise multiple regression. Vanguard spermatozoa swam more rapidly and more efficiently than did following spermatozoa, although the flagellar beat frequencies and amplitudes of the spermatozoa in the two populations did not differ. This distinction in sperm–mucus hydrodynamics could be due to reduced flagellar thrust and/or increased mucous resistance experienced by the following spermatozoa.