Vie CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. Il

A new physical method of measuring the motility of bull spermatozoa

F.A. Glover: The National Institute for Research in Dairying,
Reading,
England.

Motility can be defined as the rate of group movqfifnt of
spermatozoa in semen at natural concentrations. It is random wave
motion which is seen when looking at semen under the microscope at
low magnification, e.g. x50 and it is the character of semen which
is used in the practice of artificial insemination as the best
indication of the potential fertility of the sample1. The
established method of assessing motility is by the subjective
judgment under the microscope of the vigour of the group motion.
However, this practice is subject to all the errors well known in
such systems due to differences in concepts and skill between
operators and unavoidable bias in making Jjudgments.

Method. This paper describes an objective physical method of
measuring sperm motility. It was found that the random wave motion
deseribed above could be overcome and made to disappear by shearing
the sample between two parallel glass plates. On ceasing to shear,
the effects of the motility returned and the random wave motion
reappeared. Moreover, the rate of return of the wave motion
appeared to be related to the motility of the sample; the higher
the motility the more quickly the wave motion reappeared. Walton
put forward the same idea some years ago but the method he devised
was not offered as a practical technique for the measurement of
motility.

Instrument. A rotary shearing cell consisting of two horizontal
glass plates, 3 cm diameter 0.25 mm apart with a capacity of 0.2 ml
was built on a microscope stage and thermostatically controlled at
38°C. The top plate could rotate producing rates of shear up to
200 sec” at the periphery. Under shear the wave pattern disappeared
and the field appeared brighter. When shearing ceased, the waves
reformed and the field darkened. Hence, to detect the return of
the wave motion the change in light transmission of the sample was
used. A photoelectric cell was substituted for the microscope
eyepiece and the response of the photocell was fed into an oscill-
oscope with a long persistence screen which could display a trace
of the change in light intensity with time long enough to allow
measurement of the recovery time. Recovery times for highly motile
samples were in the region of 1 second. As samples aged motility
declined and recovery times lengthened until when the spermatozoa
became immotile the wave motion never reappeared and the recovery
time became infinite.

Evaluation. Recovery times were measured for 110 samples of

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