128 



CYCLIC CHANGES 



IV 



grow in 4 months into young fishes 240 mg in weight and 

 44 mm long. This intensive increase in weight is made 

 possible by the copious secretion of embryotrophe by the 

 ovulated follicles, the calyces nutriciae (vide p. 106), In these 

 calyces the bloodvessels develop strongly, while the cavities 

 become filled with lymph. They do not involute until some 

 time after parturition. 



As was described on p. 107, the granulosa does not usually 

 degenerate in this long-lived calyx, but changes into lutein 

 tissue, so that, in this case, we may already speak, theoretic- 

 ally, of a post-ovulation corpus luteum. From the frequency 

 of these luteinised calyces, and the simultaneous presence of 

 pre-ovulation corpora lutea we conclude that both are subject 

 to the same hypophysial influences. The times of their res- 

 pective stages of development also correspond: in December, 

 the functional phase (/5-stage) ; in January, the regression- 

 phase (y) (vide Fig. 86). In view of its association with 



months 



•.*fig^. 86. The correlation between the number of pre-ovulation corpora 

 ' \ lutea and /5-calyces during pregnancy in Zoarces viviparus. 



pregnancy, we regard oviductin as having a stimulating effect 

 on the ovary wall and on the calyces nutriciae, causing hyper- 

 trophy and marked hyperaemia of the tissues. These pheno- 

 mena are seen in Rhodeus during the growth of the ovi- 

 positor. In Zoarces, after considerable loss of ova and the 

 formation of corpora lutea (April or September) , there 

 follows a rapid restitution of ova (Fig. 86), probably as a 

 result of a strong hypophysial stimulus. 



