124 MAMMALIAN FERTILIZATION 



accordance with mammalian fertilization in the Fallopian tube 

 where only a few spermatozoa are present, about 100 in the rat 

 (Blandau and Odor, 1949), about 1000 to 5000 in the rabbit 

 (Austin, 1948b; Chang, 1951c). It also has been shown that the 

 dispersal of follicular cells is not a prerequisite of sperm penetra- 

 tion because fertilized eggs of the mouse ( Lewis and Wright, 

 1935), of the rat (Austin, 1948a), and of the rabbit (Chang, 

 1951a) are still surrounded by follicular cells. The apparent in- 

 crease of fertilizing capacity of rabbit sperm by addition of semi- 

 nal hyaluronidase reported by Rowlands ( 1944 ) was due not to 

 hyaluronidase per se but to the beneficial effect of seminal plasma 

 (Chang, 1947b). 



This observation, however, does not necessarily exclude the 

 possibility that hyaluronidase present in the individual sperma- 

 tozoon will facilitate its passage through the viscous cumulus 

 oophorus, the cements of corona radiata cells, and the mucopro- 

 tein (Braden, 1952) of the zona pellucida. This postulation, how- 

 ever, cannot reconcile the fact that dog sperm which contains 

 no hyaluronidase is still able to fertilize the dog egg which is not 

 devoid of corona radiata and zona pellucida. 



It has been suggested that the egg membrane lysin of Tyler 

 ( 1939 ) present in the spermatozoa of marine species, which helps 

 the sperm to penetrate the jelly coat, is a mucopolysaccharase 

 similar, but not identical, with hyaluronidase. This suggestion, 

 according to Mann (1954), is in need of experimental support. 

 Thus the physiological role of hyaluronidase is far from clear. It 

 may be related to the spermiogenetic function as suggested by 

 Mann, or it may function to prevent the spermatozoa from stick- 

 ing together at the end of spermatogenesis in the testes. It may 

 be associated with the activity of the Fallopian tubes which denu- 

 date ( dispersal of corona radiata ) the rabbit eggs ( Swyer, 1947 ) , 

 because in the absence of sperm the denudation of rabbit eggs 

 takes longer than in the presence of sperm ( Pincus, 1930; Chang, 

 1951a). 



A hyaluronidase inhibitor, nitrated hyaluronic acid, was re- 

 ported to effect the fertilization of rabbit eggs (Pincus et ah, 

 1948). Another hyaluronidase inhibitor, phosphoiylated hesperi- 



