FOLLICULAR DERIVATIVES IN VERTEBRATES 



Gran.c. cggcell 



III 



A 



epithelium 



egg cell granulosa - 

 I cell 



\tJ 



stroma -^ ^ , 



eggcell^ gran^hsacell 





'"- fibroblast 



gran cell 



' N - 'isS-«.,» -T-. 



eggcell 



thee a c ell . 



fibroblast 



' 1 







/'''>*" £? 

 ' 4^' 



Fig. 63. The genesis of egg and follicle in the nuclear epithelium: (a) on 



the border of a neogenic field; (b) further advanced stage of development 



in the centre of a neogenic field; (c) and (d) joining of the cellular 



material into a follicle. 



ment may be observed: an ovum is formed first, and after 

 this a primary granulosa cell (Fig. 6-3a, b). 



With this the first step is taken towards the development 

 of the two most important follicular components, i.e., the 

 ovum and the granulosa cell. Before the follicles are formed, 

 there is first a proliferation period. The ovum grows, and 

 forms, together with the 2 — 3 granulosa cells, a button-like 

 elevation, which emerges from the nuclear epithelium. At this 

 stage a number of fibroblasts are liberated from the connective 

 tissue layer of the ovary wall and arrange themselves around 

 this raised group of cells, producing fine collagen fibrils. 



