BIOLOGY OF SPERMATOZOA 



751 



ization of sperm morphology is intended 

 here, and even less is necessary by virtue 

 of many extensive surveys which, over the 

 years, have reviewed and collated the litera- 

 ture of the times, in the light of contem- 

 porary interests and in relation to other 

 areas of biologic progress (Retzius, 1909; 

 Wilson, 1925; Bradfield, 1955; Hughes, 

 1955, 1956; Franzen, 1956; Nath, 1956; 

 Colwin and Colwin, 1957; Bishop and Aus- 

 tin, 1957; Anberg, 1957; Fawcett, 1958; 

 Schultz-Larsen, 1958; Bishop, 1961). The 

 two historical surveys of Hughes (1955, 

 1956) are of particular interest to anyone 

 mindful of the past. 



Wilson (1925), among others, drew at- 

 tention to the great variation in animal 

 sperm, including the existence of nonflagel- 

 lated and nonmotile gametes among certain 

 invertebrate groups. More recently, Franzen 

 (1956), in an admirable survey of many 

 kinds of invertebrate spermatozoa, has em- 

 phasized what he believes is a significant 

 correlation between sperm morphology and 

 physiologic demands of the particular type 

 of reproductive process concerned. Con- 

 siderable attention has been paid to sperm 

 size, from the small, microscopic sea-ui'chin 

 gamete, some 40 /j. long, to the relatively 

 gigantic sperm of the hemipteran insect, 

 Notonecta glauca, which is reputed to be 

 about 12 mm. in length (Pantel and de 

 Sinety, 1906; Gray, 1955). The claim was 

 once current that, because of the difference 

 in chromosome number, a sperm population 

 displays a bimodal size-distribution curve, 

 but careful biometric studies by van Duijn 

 ( 1958) and others have shown this to be 

 untenable. More recently, differences in size 

 and shape of sperm have been demonstrated 

 in different inbred strains of mice ; the char- 

 acteristics seem to be genetically determined 

 and, when intermingled, lead to extreme 

 variation in hybrid crosses (Braden, 1959). 



Gravimetric, interferometric, and refrac- 

 tometric methods have been applied to the 

 study of sperm in an analysis of their 

 physical properties. By such procedures, one 

 can determine that bull sperm have a rela- 

 tive density of 1.280 (Lindahl and Kihl- 

 strom, 1952), a dry mass averaging 7.1 X 

 10~^ mg. (Leuchtenberger, Murmanis, Mur- 

 manis, Ito and Weir, 1956), and a total 



weight of about 2.86 X 10~^ mg. (see 

 Bishop, 1961). Human sperm contain at 

 least 45 per cent "solid material" in the 

 head, and possibly 50 per cent "solids" in 

 the tail, as assessed by the method of im- 

 mersion refractometry (Barer, Ross and 

 Tkaczyk, 1953; Barer, 1956). 



Cytochemical procedures, frequently com- 

 bined with extraction procedures, have 

 proved useful in the investigation of sperm 

 composition, particularly in tracing the 

 differentiation of cellular elements, such 

 as the Golgi apparatus and Nebenkern, 

 through spermiogenesis, and in identifying 

 the chemical nature of various structures in 

 the mature gamete. By means of PAS-posi- 

 tive tests for 1 ,2-glycol groups, for example, 

 the acrosome was found to consist of poly- 

 saccharide associated with some protein- 

 aceous material, complexed possibly as 

 mucopolysaccharide (Schrader and Leu- 

 chtenberger, 1951 ; Leblond and Clermont, 

 1952; Clermont and Leblond, 1955). Fur- 

 ther, on extraction and hydrolysis, this 

 material from guinea pig sperm proved to 

 contain galactose, mannose, fucose, and 

 hexosamine (Clermont, Glegg and Leblond, 

 1955). These are precisely the same com- 

 l)onents found by Bergman and Werner 

 (1950) in carbohydrate hydrolysates of hu- 

 man cervical mucus (see above). 



The electron micrographic studies of sper- 

 matozoa, of which there have been a great 

 number, are well summarized by Anberg's 

 fine treatise (1957) on human sperm and 

 Fawcett's eloquent review (1958) of mam- 

 malian sperm in general (Fig. 13.15). Faw- 

 cett makes the historic point that in some 

 instances the electron micrograph has con- 

 firmed details wdiich theoretically should 

 be invisible with the light microscope, but 

 were seen and described, nevertheless, by 

 an earlier generation of able microscopists — 

 the enumeration, for example, of the 11 

 tail filaments of the fowl sperm by Ballo- 

 witz in 1888. But many other features have 

 been discovered by electi'on microscopy. The 

 postnuclear cap and cytoplasmic sheath, 

 previously described as parts of the human 

 sperm' head, apparently do not exist (Faw- 

 cett, 1958). The acrosome system of the 

 human sperm is less discrete than that ob- 

 served in other types of gametes. The nu- 



