The Corpus Luteum of the Guinea Pig 83 



maintained at their full size for a long time. The corpora lutea 

 of pregnancy are enlarged when they co-inhabit ovaries con- 

 taining another set induced on the 35th day, but not when 

 ovulation was induced on the 21st day. 



Follicular growth is inhibited for four to five days follow- 

 ing the induction of ovulation in pregnancy. The induced 

 corpora lutea are incapable of sensitizing the sterile horn of 

 unilaterally pregnant guinea pigs, and their presence in very 

 late pregnancy does not interfere with parturition. 



A factor associated with decidual growth is considered to be 

 responsible for the additional growth occurring in the corpus 

 luteum of pregnancy and which is different from that main- 

 taining the size of the corpus luteum until parturition. 



j REFERENCES 



Blandau, R. J. (1949). Anat. Rec, 103, 19. 



Brambell, F. W. R., and Rowlands, I. W. (1936). Phil. Trans., 226, 

 71. 



Harrison, R. J., Harrison Matthews, L., and Roberts, J. M. (1952). 

 Trans, zool. Soc. Lond., 27, 437. 



Loeb, L. (1906). J. Amer. med. Ass., 46, 416. 



Loeb, L. (1911). J. Morph., 22, 37. 



Loeb, L., and Hesselberg, C. (1917). J. exp. Med., 25, 305. 



Nalbandov, A. V., Moore, W. W., and Norton, H. W. (1955). Endo- 

 crinology, 56, 225. 



Rand, R. W. (1955). Proc. zool. Soc. Lond., 124, 717. 



Reynolds, S. R. M. (1949). Physiology of the uterus. 2nd. Edit. 

 New York: Hoeber. 



Velardo, J. T., Olsen, A. G., Hisaw, F. L., and Dawson, A. B. (1953). 

 Endocrinology, 53, 216. 



Wright, P. L. (1942). Anat. Rec, 83, 341. 



DISCUSSION 



Harrison: I would like to ask Dr. Rowlands if he has done any histo- 

 logical or histochemical investigations on these follicles which he arti- 

 ficially ruptured during pregnancy; was there any difference in their 

 early development? 



Rowlands: No histochemical investigations have been made, but 

 with the limited number of ovaries examined by ordinary histological 

 methods there is nothing to suggest that the early development of the 

 induced corpus luteum is abnormal. 



