The Two Components of Semen 11 



Schrader, 1950; Wislocki, 1950; Friedlaender and Fraser, 1952; 

 Hancock, 1952; Melampy, Cavazos and Porter, 1952) and electron 

 microscopy (Seymour and Benmosche, 1941; Harvey and Anderson, 

 1943; Schmitt, 1944; Bretschneider and Iterson, 1947; Bretschneider, 

 1949^, b\ Grigg and Hodge, 1949; Hodge, 1949; Randall and Fried- 

 laender, 1950; Bayle and Bessis, 1951; Friedlaender, 1952; Challice, 

 1953; Bradfield, 1954). 



In a typical flagellar spermatozoon (Plate I and Fig. 1) it is usually 

 possible to distinguish three regions, viz. sperm-head, middle-piece 

 and tail, but even among closely related species, one encounters an 

 extraordinary diversity of form, size and structure. Moreover, on 

 examining the semen from a single individual, one often finds in 

 addition to the normally shaped spermatozoa, a variety of 'degener- 

 ate', 'abnormal' or 'immature' forms which represent every con- 

 ceivable deviation from the normal cell structure, from 'tapering' 

 and 'double' cells with a double head or tail, to 'giant' and 'monster' 

 cells containing several nuclei and several tails in a mass of cyto- 

 plasm. Although a high degree of sperm abnormality is undoubtedly 

 associated with subfertility, normal semen is seldom completely 

 uniform, and human semen for example, is reckoned to contain 

 as a rule, at least 20% of abnormal forms (Pollak and Joel, 1939; 

 Harvey and Jackson, 1945; Hotchkiss, 1945; Lane-Roberts et al., 

 1948; Williams, 1950). In the bull (Williams and Savage, 1927; 

 Lagerlof, 1934; Bishop, Campbell, Hancock and Walton, 1954) 

 and stallion (Bielanski, 1951), the percentage of abnormal forms in 

 semen is similarly high, in the ram on the other hand, it appears to 

 be much less. 



The shape of the head in a normal spermatozoon varies greatly; 

 it is ovoid in the bull, ram, boar, and rabbit, it resembles an elong- 

 ated cylinder in fowl and has the form of a hook in the mouse and 

 rat; in the human species, the sperm-head appears as a flattened, oval 

 body, about 4-6 ^ long, 2-6 /< wide, and 1-5 f-i thick, which is com- 

 pressed at the anterior pole into a thin edge. 



The main part of the head is occupied by the nucleus, filled by 

 closely-packed chromatin which consists largely of deoxyribonucleo- 

 protein and gives a positive Feulgen (nucleal) reaction with Schiff"'s 

 fuchsin-sulphurous acid reagent. The anterior part of the nucleus 

 is covered by a cap-like structure known as the acrosome. The 



