BIOLOGY OF SPERMATOZOA 



765 



thetic ability even after ejaculation. Such 

 metabolic cofactors as ATP, for example, 

 are most certainly synthesized (at least 

 from ADP), at the expense of organic sub- 

 strates, throughout the motile life span. 

 More complex substances may also be 

 synthesized. Hakim (1959) has reported 

 that polynucleotide phosphorylases can be 

 extracted from human sperm which, when 

 incubated with nucleotide phosphates, 

 cause the formation of dinucleotides, as 

 determined chromatographically. Thus, for 

 example, a mixture of ADP and guanosine 

 diphosphate (GDP), in the presence of 

 suitable enzyme, forms some ADP-GDP. 

 In another type of study employing intact 

 bull sperm, Bishop and Lovelock indicated 

 that C^*-labeled acetate is incorporated 

 into fatty acid (see Austin and Bishop, 

 1957). 



The possibility of jirotein synthesis by 

 sperm was suggested by Bhargava (1957), 

 who reported the incorporation of labeled 

 amino acids into the protein fraction of bull 

 spermatozoa as assayed by radioactivity 

 counting. These conclusions have since been 

 contradicted by Martin and Brachet (1959) 

 who suggest, on a basis of autoradio- 

 graphic data, that the uptake and synthesis 

 can be attributed to cellular components 

 other than to the sperm in the sample. 

 This finding falls more nearly in line with 

 the general conclusion that RNA, essential 

 for protein synthesis, is absent from mature 

 sperm or is present in only very small 

 amounts (Brachet, 1933; Friedlaender and 

 Frasei-, 1952; Leuchtenberger, Leuchten- 

 berger, Vendrely and Vendrely, 1952; 

 Mauritzen, Roy and Stedman, 1952). In 

 this connection it is of interest to recall the 

 observations of Wu, McKenzie, Fang and 

 Butts (1959) on the contrasting metabolic 

 capacities of testicular and seminal bull 

 sperm. Relatively clean preparations of 

 spermatozoa expressed from incised testis, 

 but not sperm from the ejaculate, can oxi- 

 dize glucose by way of the hexose mono- 

 phosphate shunt, thereby supplying a source 

 of ribosc which is available for RNA in 

 the cai'lici' stages of sperm differentiation. 



IX. Sperm Flagellation 



The characteristics and mechanics of 

 s]ierm movement are discussed in con- 



siderable detail in several recent reviews 

 dealing with both invertebrate and verte- 

 brate material (Gray, 1953, 1955, 1958; 

 Gray and Hancock, 1955; Bishop, 1961). 

 Sperm motility, closely related to muscular 

 contraction, on the one hand, and to general 

 flagellar and ciliary activity, on the other, 

 represents an important physiologic process 

 with implications l)eyond the specific be- 

 havior of the gametes. For the present con- 

 text, however, only certain more general 

 aspects of the problem are pertinent. 



By the tiirn of the century the signifi- 

 cance of the flagellum for sperm motility 

 was well established (see Wilson, 1925). 

 As early as 1898, Engelmann had succeeded 

 in cutting off the tails of frog spermatozoa 

 to find that the flagella continued to move 

 if the separations were made close to the 

 heads. Ciaccio (1899) and particularly 

 Koltzoff (1903) discussed the elementary 

 mechanisms of flagellation and went so far 

 as to compare the process with contraction 

 of muscle. In 1911, Heidenhain postulated 

 that the chemical energy rec}uired for mo- 

 tility must be distributed throughout the 

 flagellum, a concept generally conceded to- 

 day (Gray, 1958). Ballowitz (1888, 1908) 

 emphasized the significance of the longi- 

 tudinal fibrils of the axial bundle for mo- 

 tility. In the history of sperm biology these 

 two decades, immediately before and after 

 1900, constitute the "Age of Flagellation." 



A. WAVE PATTERNS 



Largely through the efforts of Sir James 

 Gray (1953-1958) many details of the proc- 

 ess of flagellation have been recorded, most 

 attention having been focused on the sperm 

 of the sea urchin and bull. Although there 

 exists much natural variation among species 

 in the overt characteristics of the phenome- 

 non, basically the same fundamental mech- 

 anism is involved. Propagated waves 

 originate at the base of the flagellum and 

 progress distally toward the tip. The major 

 bending-couple is two-dimensional, but as 

 it sweeps distally it is accompanied by, or 

 is converted into, a three-dimensional wave 

 which gives the sperm a helical spin about 

 the axis of forward progression (Gray, 1955, 

 1958). In squid sperm under experimental 

 conditions the two components of move- 

 ment, lateral vibration and rotation, can 



