MORPHOGENESIS OF THE MAMMALIAN OVARY 357 



the adult ovar3\ What has been spoken of as the intermediate 

 zona is most distinct in the growing o\'ary in the postpartum 

 period (fig. 10), losing its identity in the adolescent and adult 

 period (figs. 14 and 15) as part of the zona parenchymatosa. The 

 zone vascularis, on the contrary, can hardly be said to exist as 

 such in the fetal ovary, and becomes more distinct as maturity 

 is approached. ^Marginal growth, along the line where ovary 

 and ovarian ligament join (represented by the white line of the 

 adult human ovary) appears to play an important part in the 

 assumption of the adult morphology. In the marginal zone 

 growth continues apparently as long as the increase in size con- 

 tinues in the presexual period (approxunately four months), the 

 growth including the stroma as well as the parenchyma (elements 

 of epithelial origin). 



The zones of the ovary are but the expression of the mode of 

 growth and tj^pe of blood supply, and hence possess no intrinsic 

 or genetic significance such as the cortex and medulla of the 

 suprarenal organ, for example, possess; but even so, the termin- 

 ology of the regions of the mammalian ovary is not altogether 

 satisfactory. The older terms, medulla and cortex, as well as the 

 B.N.A. terms, zona vascularis and zona parenchymatosa are both 

 employed and are both appHed to the mature organ. The latter 

 terms may be very satisfactorily employed in the description of 

 the adult ovary but they are not so applicable in the developing 

 structure due to the mode of growth. The terms introduced by 

 Sainmont ( '05) in his study of the development of the cat's ovary 

 and subsequently adopted in the monograph by von Winiwarter 

 and Sainmont ( '08) are quite serviceable and are those which 

 will be used here, with two or three modifications which render 

 them more serviceable as expressions of the present writer's con- 

 ception of the morphogenesis. The primitive cortex becomes the 

 definitive cortex during de^^elopment. This is a somewhat more 

 restricted use of the term than that usually emplo3^ed. It repre- 

 sents therefore only the outer portion of the definitive cortex in the 

 more usual use, or the zona parenchymatosa. It is, however, 

 as employed by His ('65) in the cat's ovar3^ The outer portion 

 of the nucleus epithelio-stromalis centralis (of Sainmont) is the 



