52 EGG AND SPERM SUBSTANCES 



1950b; Riinnstrom, Wicklund, and Low, 1954) the possibility of 

 release of the responsible agent (s) at fertilization under normal 

 conditions. However, the situation is complicated by cytofertilizin 

 which, according to Motomura ( 1950a, 1953a,b ) is also released 

 by the egg at fertilization. Antifertilizin and cytofertilizin might 

 be expected to interact with mutual neutralization. The two agents 

 would not be expected to exist together in active form. Even if 

 they were released separately they should interact in the perivi- 

 telline space, and only the agent in excess should be detectable. 

 In view of this apparent inconsistency, the release of antifertilizin 

 and cytofertilizin must be re-examined with a strict accounting 

 of both agents. 



Agents from Sperm 



Several agents have been obtained from sperm which may 

 function in fertilization. These include the antifertilizin from 

 sperm, egg membrane lysins, and preparations which affect the 

 physiological activity of sperm. Before considering these it should 

 be emphasized again that agents in sperm extracts which act 

 upon gametes may be products of the method of preparation. 

 Such agents may not exist in an active form and function in fer- 

 tilization under physiological conditions. 



Antifertilizin from Sperm 



Agglutination of sperm by fertilizin implies the existence of a 

 specific receptor on the sperm surface (Fig. 1). The agent, anti- 

 fertilizin,* should have biological properties similar to those of 

 the antifertilizin from eggs. It should occur in appreciable 

 amounts on the sperm surface. In solution it should neutralize 

 fertilizin, precipitate egg jellies and agglutinate eggs. Prepara- 

 tions with such properties have been obtained from sea urchin 

 sperm by heating (Frank, 1939), freeze thawing (Tyler, 1939b), 

 extraction with weak acid ( Tyler and O'Melveny, 1941 ) , or by 



* Sperm antifertilizin (Tyler and O'Melveny, 1941) = Sperm receptor 

 (Lillie, 1913a, 1914) = Androgamone II (Hartmann et al, 1940) = Jelly 

 precipitating factor from sperm, abbreviated JePpF (S) (Hultin et al., 

 1952). 



