MORPHOGENESIS OF THE MAMMALIAN OVARY 349 



I have termed a process interpretation and an ultimate particle 

 interpretation of structure. Furthermore there are two aspects 

 that may well be quite distinct so that the problem would be 

 essentially doubled — the determination of sex on the one hand, 

 and the origin and development of the sexual organs on the other. 



From whatever point of view the development of the verte- 

 brate reproductive system may be considered, interest must center 

 in the essential organs — the ovary and testis — and the question as to 

 whether or not they, as well as the duct system, exhibit the sexual 

 dimorphism is particularly pertinent. Waldeyer ('70) suggested 

 that the potentialities for the development of both ovary and 

 testis existed in the same individual and that the male and fe- 

 male gonads developed from different portions of the germinal 

 ridge. Van Beneden ( '80) from the conditions in the adult bat 

 advanced the hypothesis that ovary and testis were homologous 

 or at least analogous in their morphology, comparing the med- 

 ullary cords (cordons pleins) to the tubuli contorti (seminifer- 

 entes) the medullar}^ tubes (cordons tubulaires) to the tubuli 

 recti, the reticular body (corps reticule; that is, rete ovarii) to the 

 rete testis (Halleri). Subsequent work on the development of 

 the ovary by Mihalkowics ('85), Janosik ('85) ('88), Coert('90), 

 Allen ( '04), and Winiwarter ( '00) particularly have seemed to jus- 

 tify the suggested homologization. It is the concensus of opinion 

 of these later writers that the medullary cords are developed 

 from the germinal epithelium, and are hence directly pf meso- 

 thelial origin, they being early formed and succeeded later by the 

 growths that furnish the functional germ cells of the ovary, the 

 frequently described Pfluger's egg tubes or cords. It should be 

 stated, however, that the older interpretation of the origin of the 

 medullary cords from the Wolffian body, as held by Waldeyer, 

 Balfour, and Braun, is still adhered to by 0. Hertwig ('11) and 

 Tourneux ('09), the latter regarding the tubuli contorti of the 

 testis as developed from the same source, while the former de- 

 rives them from the germinal epithelium (mesothelium). 



The development of the rete ovarii (and the rete testis) seems 

 unquestionably to demand further investigation to determine its 

 mode of origin. Coert ('90), Mihalkowicz ('85), Janosik ('85), 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 15, NO. 3 



