TUBAL HISTORY OF UXFKRTILIZl^D EGGS 71 



to obtain the full complement as indicated by the corpora 

 lutea count. They are either rapidly resorbed or washed 

 out into the vagina. The cytoplasm of eggs recovered from 

 the uterus shows distinct evidences of degeneration (Fig- 

 ures 8 and 9). 



The persistence of the corona radiata for some time after 

 ovulation occurs regularly not only in the rabbit (cj. Yamane, 

 1930, 1935) but also in the mouse CLong, 1912), the rat 

 (Gilchrist and Pincus, 1932), the dog fEvans and Cole, 1931), 

 and man (Allen, Pratt, Newell and Bland, 1930a). It is 

 notable that opossum ova with no surrounding cumulus 

 mass enter the uterine portion of the oviduct in approx- 

 imately twenty-four hours, whereas all available information 

 indicates that in the higher mammals unfertilized ova enter- 

 ing the uterus do so at approximately 3 H days after ovula- 

 tion. In the rat (and probably also the mouse) unfertilized 

 ova apparently degenerate in the uterine portion of the 

 tubes (Long and Evans, 1922; Mann, 1924). Albumen 

 deposition about tubal ova occurs in the rabbit and opos- 

 sum; in most other mammals the ovum traverses the tube 

 surrounded only by the zona pellucida. 



The dissolution of the cumulus mass surrounding newly 

 liberated ova seems to involve a definite process in the 

 tubes and is in all probabiUty not due to an autogenous 

 change in the cumulus cells themselves. In guinea pigs the 

 fresh cumulus mass is so tenaciously adherent that it cannot 

 be completely removed by dissection (Squier, 1932). Gil- 

 christ and Pincus (1932) found that rat ova incubated in 

 Ringer's solution did not become free of adherent cells even 

 after many hours. In rabbit ova grown in blood plasma a 

 fibroblast-like outgrowth of the cumulus cells occurs but 

 nonetheless the radial connections to the zona pellucida 

 are not lost (Pincus, 1930). The writer has also observed a 

 similar outgrowth from the cells surrounding cultured hu- 

 man ova, but the extremely tenacious covering of follicle 

 cells is not lost. The likelihood that a slow enzymatic process 

 is involved in the freeing of the adherent cells is substanti- 



