SPERM, OVA, AND PREGNANCY 



be separated and analyzed individually 

 (Bishop, 1958f). Wave co-ordination in- 

 volves not only the initiation of the beat, 

 which may be a function of the basal gran- 

 ule, but also the propagation of the conduc- 

 tion wave along the flagellum. The velocity 

 of wave propagation has been calculated for 

 bull sperm to be 600 to 700 /x per sec. 

 (Bishop, 1961). 



The frequency of beat, stroboscopically 

 determined, is on the order of 20 per sec. 

 for the bull and 15 per sec. for man (Ritchie, 

 1950; Rothschild, 1953; Rikmenspoel, 1957; 

 Zorgniotti, Hotchkiss and Wall, 1958). 

 Wave amplitude in bull sperm is 8 to 10 fi, 

 about 20 times the diameter of the tail. 

 These values are at best only first approxi- 

 mations, because wave characteristics 

 change not only with progression along the 

 length of the flagellum, but also with en- 

 vironmental conditions such as temperature 

 and viscosity of the medium. 



B. SPERM VELOCITY 



Many attempts have been made to de- 

 termine the speed of sperm travel (see 

 Bishop, 1961). As a general rule, the 

 methods used give data for translatory 

 rather than absolute velocities (Table 

 13.13). Speeds up to 350 /* per sec. have 

 been recorded for bull sperm. Rikmenspoel 

 (1957) has presented an extensive correla- 

 tion of the variations in bull sperm velocity 

 with changes in frequency and amplitude 

 of wave formation and with alterations in 

 viscosity and temperature of the environ- 

 ment. The effect of current flow on stallion 

 sperm velocity was demonstrated by Yam- 



TABLE 13.13 



Translatory velocities of mammalian 



spermatozoa, in vitro 



(Buffered saline or saline-plasma, 37°C.) 



ane and Ito ( 1932 ) . They found that sperm 

 orient themselves by rheotaxis, or are 

 oriented physically, against a current, and 

 that up to a limit, as the opposing flow is 

 increased, the speed of movement also in- 

 creases. When the opposing current flow 

 was varied from to 20 ju. per sec, sperm 

 velocity increased from 87 to 107 yu, per sec. 

 Under the conditions of the experiment, the 

 results might be attributable merely to the 

 direction given the sperm, thereby reducing 

 the randomness of movement. Nevertheless, 

 these findings may have some bearing on 

 the problem of active sperm transport in 

 vivo, where ciliary or other currents play 

 a role. From a comparison of the data on 

 sperm velocities (Table 13.13) and those 

 previously cited on sperm transport, the 

 conclusion is inescapable that in most mam- 

 mals, migration is not dependent on active 

 swinnning movements alone. 



C. HYDRODYNAMICS 



Initiated by the theoretical speculations 

 and mathematical derivations of Sir Geof- 

 frey Taylor (1952), a considerable body of 

 information has accrued which permits an 

 evaluation of the mechanics and forces in- 

 volved in si)erm movement (Gray and Han- 

 cock, 1953; Hancock, 1953; Rothschild, 

 1953; Machin, 1958; Xelson, 1958b; Carl- 

 son, 1959). From these considerations it is 

 clear that a spiral or three-dimensional 

 pattern of flagellation is more eflficient than 

 a two-dimensional wave motion; Taylor 

 calculates that the resulting sperm velocity 

 in the former case may be up to twice as 

 great, depending on the configuration of the 

 sperm cell, for a given amount of energy ex- 

 pended. Employing these mathematical der- 

 ivations and experimental data for wave 

 characteristics such as frequency and ampli- 

 tude, Gray and Hancock (1953) found 

 good agreement in calculated and observed 

 values for the velocity of sea-urchin sperm 

 of about 190 fx per sec. The power output 

 required to effect this activity has also 

 been calculated. For sea urchin sperm, 

 Carlson (1959) obtained a value of about 

 3 X 10~" erg per sec. per sperm. Compa- 

 rable figures for bull sperm have been esti- 

 mated as ranging from 2xl0~^to3x 

 10~^ erg })er sec. per sperm, depending on 



