76 



THE EGGS OF MAMMALS 



Yamane (1930) has ascribed the phenomenon of folHcle 

 cell dispersion to the presence of a proteolytic enzyme in the 

 spermatozoa. He was able to secure a similar dispersal of 



follicle cells from sperm sus- 

 pensions heated to 60° C. and 

 from preparations of pancrea- 

 tin containing trypsin. Yam- 

 ane (1930) believes that this 

 J "^ '^^^^P^^^' J^^H proteolytic enzyme is also re- 

 f f^&^S^X€jli^S sponsible for the activation 



of the egg since he observed 

 ''polar" bodies formed in 

 rabbit ova exposed to the 

 suspensions of dead sperm 

 and to the enzyme prepara- 

 tions. 



Pincus and Enzmann 

 (1935) have examined this 

 situation in some detail. 

 Sperm suspensions free of 

 seminal fluid were obtained 

 from the vas deferens of adult 

 rabbit males. Dilutions were 

 made with a buffered Ringer- 

 Locke solution at pH 7.3 — 

 7.5. The ova were taken 

 at 12 H to 153^ hours after 

 copulation from rabbit does 

 mated to sterile (vasecto- 

 mized) males ; these ova were 

 invariably well embedded in 

 the massed follicle cells. The 

 procedure followed was to 

 place the massed ova in the sperm suspension and incubate 

 for at least two hours. All ova were examined at two hours 

 after semination and in some instances where no obvious 

 signs of fertilization were observed incubated for 12 hours. 



Fig. 24. Rat ovum of Fig. 23 

 after 2 hours with Hving 

 sperm. Note absence of folhcle 

 cells and protrusion resembling 

 a polar body. (From the Aiia- 

 tomical Record.) 



Fig. 25. R.it ovum recovered 11 

 hours after sterile mating and in- 

 cubated with living sperm for 2 

 hours. Note shrunken vitellus and 

 two polar bodies. (From the Ana- 

 tomical Record.) 



