354 B. F. KINGSBURY 



so-called medullary cords, egg cords, rete ovarii, and stroma — ■ 

 have already appeared, can nearly be contained in a single large 

 Graafian follicle of the adult organ. An understanding of the 

 moi'phological transformations that lead to the establishment of 

 the adult organ is to be found only in a correct analysis of its 

 growth. In the published descriptions of the development of 

 the ovary the marked and rapid increase in si7;e, it is felt by the 

 writer, is frequently not adequately expressed or given due con- 

 sideration. Thus, the so-called egg tubes of Pfliiger are spoken 

 of as 'down-growths' of the surface (germinal) epithelium, 

 whereas they more exactly represent cell trails left behind in the 

 advancement of the surface as the organ increases in size. This 

 does not apply apparently to the earliest proliferative growth of 

 the germinal epithelium in the indifferent period, in which appar- 

 ently there is an actual displacement of the underlying tissue 

 (Felix '11 ). 



The medullary cords in similar manner represent the earliest 

 proliferations of the mesothelium whose immediate activity ap- 

 parently largely determines the early growth. Whether or not 

 the mesothelium loses its connection with these early formed 

 masses, the stroma growing between as a tunica albuginea primi- 

 tiva as described by Sainmont, I cannot of course consider, since 

 the stages studied do not include the early development. In 

 the 75-mm. fetus a sharp separation into primitive medulla and 

 cortex by a distinct stromal layer does not exist. 



In the further prenatal growth of the ovary, as illustrated in 

 the stages examined, the ovary more than doubles its diameters. 

 This size increase is due to the double activity of the epithelial 

 elements (ova and indifferent or follicle cells) and of the stroma. 

 The surface mesothelium retains throughout its connection with 

 the epithelial masses to which the term egg cords may be applied 

 and which early assumed a more elongated form due to their 

 greater separation by strands of stroma and the increase in size 

 of the ovary due to their growth and that of the stroma as well. 

 The seat of proliferation lies mainly peripherally in the primitive 

 cortex and the growing zone becomes more superficial as develop- 

 ment proceeds. Cell divisions also occur frequently in the sur- 



