756 



SPERM, OVA, AND PREGNANCY 



gellum and are known to be involved in the 

 Embden-Meyerhof glycolytic process, in- 

 clude hexokinase, phosphohexoisomerase, 

 phosphohexokinase, aldolase, enolase, and 

 lactic dehydrogenase (Mann, 1949, 1954). 

 Cytochrome oxidase, determined both man- 

 ometrically (Zittle and Zitin, 1942) and 

 spectrophotometrically (Nelson, 1955a), is 

 present in the tail fraction of bull sperm, 

 and the complete cytochrome system can be 

 demonstrated in flagellar preparations which 

 include the midpieces as well (Mann, 1954). 

 From what is known about mitochondrial 

 activity in general, one assumes that most, 

 if not all, of the enzyme systems associated 

 with respiration, oxidative phosphorylation, 

 and electron transport through the cyto- 

 chrome system are concentrated in the 

 sperm midpiece. Succinic dehydrogenase can 

 be demonstrated in flagellar fractions both 

 by biochemical and cytochemical methods 

 (Mann, 1954; Nelson, 1955a; Kothare and 

 De Souza, 1957). Nelson (1959) has further 

 been able to show in frozen-dried sections of 

 the rat sperm flagellum what seems to be 

 succinic dehydrogenase activity in the out- 

 ermost longitudinal fibers of the tail. 



The sperm flagellum, at least in man and 

 bull, when tested cytochemically, gives posi- 

 tive reactions for acid phosphatase, and the 

 bull sperm tail shows alkaline phos])hatase 

 activity as well (Wislocki, 1950; ]\lelampy, 

 Cavazos and Porter, 1952). Both types of 

 phosphatase have been cytochemically lo- 

 calized in the midpiece of the rat sperm 

 (Friedlaender and Fraser, 1952; Melampy, 

 Cavazos and Porter, 1952). The precise 

 functions, however, of these enzymes in the 

 sperm are not clear. 



One or more adenosinetriphosphatases 

 (ATPases) have been extracted from or 

 demonstrated in the flagella of inverte- 

 brate and mammalian spermatozoa (Felix, 

 Fischer, Krekels and Mohr, 1951; Nelson, 

 1954, 1955b; Engelhardt and Burnasheva, 

 1957; Burnasheva, 1958; Hoffmann-Berling, 

 1955; Bishop and Hoffmann-Berling, 1959). 

 In frozen-dried sections of rat sperm fla- 

 gella, ATPase has presumably been visual- 

 ized in association with the outermost array 

 of fibrils (Nelson, 1958a). 



In the head of the mammalian sperm, 

 only acid and alkaline phosphatases have 



been reported and these determinations were 

 achieved by cytochemical localization (Wis- 

 locki, 1949, 1950; Melampy, Cavazos and 

 Porter, 1952; Friedlaender and Fraser, 

 1952). 



Thus far, no enzymes have been identified 

 in the mammalian sperm head which com- 

 pare with the invertebrate sperm lysins, be- 

 lieved to play some role in egg penetration 

 (Tyler, 1948). Hyaluronidase, which effec- 

 tively disperses the cumulus cell mass 

 around mammalian ova, is present on the 

 sperm but has not been localized in any one 

 region. Buruiana (1956) found that hyalu- 

 ronidase activity is common to mammalian 

 sperm, whereas trypsin activity is charac- 

 teristic of bird sperm; of the species studied, 

 only the rabbit sperm showed both types of 

 enzymatic activity. Amylase has been dem- 

 onstrated in bull sperm, but because of the 

 violence of the extraction procedure, little is 

 known as to its site of action (Lundblad and 

 Hultin, 1952). Other enzymatic activities 

 have been found in intact sperm or cell 

 homogenates, such as aconitase in bull 

 (Lardy and Phillips, 1945; Humphrey and 

 Mann, 1948), cholinesterases in boar and 

 guinea pig (Sekine, 1951; Sekine, Kondo 

 and Saito, 1954; Grieten, 1956), and gly- 

 cosidases and sorbitol dehydrogenase in ram 

 (Conchie and Mann, 1957; King and Mann, 

 1958). Sorbitol deiiydrogenase may serve to 

 convert the seminal plasma constituent, 

 sorbitol, to fructose, a normal metabolic 

 substrate for spermatozoa. 



D. THE SPERM SURFACE 



As far as can be determined from electron 

 micrographs, the sperm cell membrane is 

 identical with, or at least derived from, the 

 spermatid membrane. In the mature ram 

 sperm, as in many invertebrate sperm, the 

 membrane was claimed to swell osmotically 

 in response to hypotonic changes in the 

 medium (Green, 1940). This is not true of 

 bull sperm (Rothschild, 1959) ; in fact most 

 mammalian sperm are resistant or indiffer- 

 ent to osmotic changes (Emmens, 1948; 

 Pursley and Herman, 1950; Blackshavv, 

 1953a, b; M. W. H. Bishop, 1955). This 

 feature is in contrast to the selective per- 

 meability with respect to many organic 

 molecules, both charged and uncharged 



