io8 FOLLICULAR DERIVATIVES IN VERTEBRATES III 



of the rupture, through the pressure of lymph, and the auto- 

 lysed, liquefied, granulosa tissue (Fig. 75e). 



Thus we see that, in each of these groups, certain con- 

 ditions repeat themselves, leading to analogous forms, 

 although the origin and differentiation of the tissue and the 

 moment of its formation show considerable mutual dif- 

 ferences. 



§ 6. THE DERIVATIVES OF FOLLICULAR INVOLUTION 

 AND THE INTERSTITIUM 



The regressive phase of the various, often relatively large 

 follicular derivatives may, according to the origin of their 

 tissue and their function, or according to the species, adopt 

 various forms. 



a. The corpus candicans. In the case of the thecal atretic 

 follicular derivatives a moment arises when the secretion of 

 the lutein cells stops, and the connective tissue nature of the 

 theca gets the upper hand again. In this, the thecal tissue 

 frequently proliferates radially towards the centre. The 

 originally thin hyaline membrane in the outer zone of the 

 theca expands, forming thick folds. This is the membrane of 

 Slavyanski. Long after the other theca cells have degenerated 

 and migrated it may still be seen in the stroma of the ovary 

 (Fig. 70, Fi). 



/5. The corpus albicans. As a rule the granulosa lutein 

 cells are destroyed by degeneration, and are finally resorbed 

 by leucocytes. The theca, however, which surrounds the 

 corpus luteum either in the form of a layer of connective 

 tissue or as theca-lutein cells, participates in the formation of 

 glands, develops after its secretion has finished and pro- 

 liferates through the granulosa tissue in course of dissolution. 

 In this process, too, a membrane of SLAVYANSKI may be 

 observed. Finally, this remnant shrinks and passes back into 

 the stroma (Fig. 70, F3 — F4). 



6. The interstitium. The originally secreting tissue does 

 not in all species die with the death of the gland. Remaining 

 lutein cells may pass en bloc into the ovarian stroma. 



