Sperm Movement 

 Problems and Observations* 



LORD ROTHSCHILD 



Department of Zoology, Cambridge University, Cambridge, England 



The speed at which a mammalian spermatozoon moves makes it 

 difficult to see any details down the microscope with the naked eye. 

 The alternatives are high-speed cinematography or slowing down the 

 sperm movement. A film was made when the movements of the 

 spermatozoa were slowed by increasing the viscosity of the suspend- 

 ing medium from its normal value of about 1 centipoise to 3000 

 centipoises. The film showed that, under these experimental condi- 

 tions, bull spermatozoa move by passing two-dimensional waves of 

 bending from the front to the back ends of their tails. The amplitude 

 is not constant, nor is the wave form sinusoidal. In the film one sper- 

 matozoon, or spermatozoa, were seen moving faster than the others 

 and appeared to have two tails. Possibly this was a monster. More 

 probably it was two spermatozoa, whose tails were beating in phase, 

 on top of each other. If the characteristics of the tail waves, which 

 are called motility parameters, are unaffected by such proximity 

 (which seems to be so in this case), one might expect, from hydro- 

 dynamic considerations, that two spermatozoa in such a position 

 would travel faster than one alone (Taylor, 1951). Whether there is 

 any reason for sperm tails to get into phase when close to each other 

 is a question which will be discussed later. 



MORPHOLOGY OF SPERM MOVEMENT 



Surprising as it may seem, there does not seem to be universal 

 agreement in 1960 as to whether the waves which pass along the 

 tail of a bull spermatozoon are planar, that is to say two-dimensional, 



* The work described in this review is supported by the British Agricultural 

 Research Council. 



