Protein Constituents of Spermatozoa 97 



(1942) they are needed to create and keep up a sufficiently high con- 

 centration of hyaluronidase to permit the denudation of the egg. 

 This hypothesis was put to the test by Rowlands (1944) who found 

 that it is possible to increase the fertilizing capacity of a subnormal 

 number of rabbit spermatozoa by the addition of hyaluronidase in 

 the form of extracts from whole dilute rabbit semen. Similar results 

 were reported by Leonard and Kurzrok (1945, 1946). 



In view of all this, little wonder that many investigators became 

 attracted by the possibility of the therapeutic application of hyalu- 

 ronidase in infertility. In fact, several enthusiastic reports appeared 

 of success in human infertility of oligospermic origin, achieved by 

 the addition of bovine testicular hyaluronidase to human semen. 

 However, subsequent investigations failed to bear out the claim 

 that hyaluronidase can enhance the fertilizing capacity of sperma- 

 tozoa. According to Chang (1947Z), 1949) the earlier positive results 

 obtained with extracts from whole semen should be attributed not 

 to hyaluronidase but to the effect of the seminal plasma as such. 

 Similarly, the concept that a high sperm concentration in the vicinity 

 of the egg is needed to denude the ovum from its cumulus, has been 

 questioned by Leonard, Perlman and Kurzrok (1947), Austin (1948), 

 and Austin and Smiles (1948) who demonstrated clearly that sperma- 

 tozoa can in fact penetrate rat ova which are still enclosed in the 

 cumulus. Presumably, the hyaluronidase charge carried by the sper- 

 matozoa makes it possible for the individual sperm to 'burrow' its 

 way through the viscous gel which cements the follicular cells. 

 This, however, need not necessarily involve the dispersion of the 

 cumulus, which process is probably aided by the mechanical action 

 of the ciUa or by some other tubal factor. 



Another development in the field of sperm hyaluronidase per- 

 taining to the role of this enzyme in fertilization, has been the 

 attempt to use certain inhibitors of hyaluronidase as systemic con- 

 traceptives. Among the inhibitors of hyaluronidase, presumably 

 competitive in nature, are several derivatives of hyaluronic acid 

 obtained by acetylation or nitration, also heparin, and a number 

 of other anticoagulants and mucopolysaccharides, including a sub- 

 stance present in blood serum (Ferraro, Costa and Pelegrini, 1948; 

 Hadidian and Pirie, 1948; Pincus, Pirie and Chang, 1948; Meyer 

 and Rapport, 1952). Another two groups of inhibitors, some of 



