80 The Biochemistry of Semen 



made in studies concerning spermatozoal antigens and antibodies, 

 culminating in the development of several antispermatozoal sera, 

 active not only tov^ards heterologous but also homologous, sperma- 

 tozoa. So far, most attempts to immunize a female against sperma- 

 tozoa of her own species, as a means of 'serological contraception', 

 have been failures. A wealth of data on sperm immunology and 

 sperm-serum interaction can be found in articles by Metchnikoff 

 (1900), Moxter (1900), Godlewski (1912), Kato (1936), Henle and 

 Henle (1940), Parkes (1944), Snell (1944), Tyler (1948), Smith (1949), 

 Docton et al. (1952), and Kibrick et al. (1952). 



One of the first diluents used in veterinary practice for the in- 

 semination of cattle in Russia, was Milovanov's 'SGC-2 dilutor' 

 (13-6 g. Na2S04, 12 g. glucose, and 5 g. Witte's peptone, in 1 1. 

 water). The same investigator experimented also with so-called 

 gelatinized diluents which contained apart from salts and glucose, 

 some gelatin, so as to endow the fluid with a jelly-like consistency. 

 One such diluent developed for the storage of bull semen, has been 

 the 'GPC-3-G dilutor' (1-7 g. Na2HP04, 007g. KH0PO4, 008 g. 

 Na2S04, 2-85 g. glucose, 5 00 g. gelatin, 1 1. water.) A method 

 adopted by the Russian workers was to use the diluted semen for 

 insemination in the form of gelatin capsules. A major advance in 

 the technique of semen storage has been the introduction by 

 Phillips and Lardy (1939, 1940) of the 'egg-yolk-phosphate diluent' 

 which became widely established both in America and in Europe 

 for the purpose of preservation, transportation and insemination of 

 bull semen. It is prepared by mixing freshly separated egg yolk with 

 an equal volume of phosphate buffer, pH 7-4 (2 g. NagHPOi- OHgO^ 

 0-2 g. KH2PO4, made up to 100 ml. with water). For actual storage, | 

 and subsequent insemination, bull semen is diluted up to 100 times, 

 or more, with the egg-yolk phosphate dilutor. In addition to pre- 

 serving sperm viability, the dilutor protects the spermatozoa effi- 

 ciently from 'temperature shock', that is from the rapid immo- 

 bilization induced by sudden cooling of semen to 5-10°, the usual 

 temperature for storage of semen (Chang and Walton, 1940; Easley, 

 Mayer and Bogart, 1942). The chemical nature of the protecting 

 substance is unknown but there are indications that it is an acetone- 

 soluble but ether-insoluble, compound (Mayer and Lasley, 1944). 



Many recommendations have been made to improve the egg-yolk- 



