MORPHOGENESIS OF THE MAMMALIAN OVARY 377 



fundamental plan of the system, and the underlying mode (meta- 

 bolic attitude) that determines the direction taken — the ''deter- 

 mination of sex. " In the development of the human ovary and 

 testis, for example, Felix has shown that in both sexes there is 

 the same fundamental material which is worked over, so to speak, 

 along one or the other lines of differentiation. 



It was the suggestion, of Wilson I believe, that sex and the sex- 

 ual characters might be differently determined, the latter by 

 the heterochromosome. Suggesting in turn that the hetero- 

 chromosome stands for the former; instead, it might be stated in 

 closing as at the beginning of this paper, that the evidence indi- 

 cates a quantitative rather than a qualitative sex difference, a 

 different metabolic habit, degree or tendency that determines the 

 result. 



SUMMARY 



1. In the development of the ovary of the cat, growth is mainly 

 peripheral and marginal. 



2. Differentiation therefore follows centrifugally. 



3. The epithelial elements (parenchyma) occur in the form of 

 cords. 



4. Medullary cords and egg cords are not to be sharply 

 distinguished. 



5. The growth determines the appearance of fairly definite 

 zones: (a) cortical, (b) intermediate, (c) epithelial stromal. 



6. Degenerations occur throughout the period of growth and 

 in the adult period. 



7. In general, the degenerations follow a centrifugal course. 



8. The stroma obviously plays an active and important part 

 in ovarian growth. 



9. The primitive cortex is interpreted as directly forming the 

 definitive cortex containing the primary follicles. 



10. No evidence was found of a new formation of ova just prior 

 to sexual maturity. 



11. Profound degeneration of the early formed Graafian 

 follicles occurs, being most marked before the advent of sexual 

 maturity. 



