836 EMBRYOLOGY 



oped into the testicles for the male, or the ovaries for the female. At 

 their external borders are two ducts on either side, one of which, the 

 internal, is called the duct of the Wolffian body. This finally disap- 

 pears in the female, but it is developed into the vas deferens in the 

 male. The other duct, which is external to the duct of the Wolffian 

 body, disappears in the male, but it becomes the Fallopian tube in the 

 female. This is known as the duct of Miiller. Behind the Wolffian 

 bodies, are developed the kidneys and the suprarenal capsules. 



As the development of the Wolffian bodies attains its maximum their 

 structure becomes somewhat complex. From their proper ducts, which 

 are applied directly to their outer borders, tubes make their appearance 

 at right angles, which extend into the substance of the bodies and 

 become somewhat convoluted at their extremities. 

 These tubes communicate directly with the ducts, 

 and the ducts themselves open into the lower 

 part of the intestinal canal opposite the point of 

 its communication with the allantois. The tubes 

 of the Wolffian bodies are simple, terminating in 

 single, somewhat dilated, blind extremities, are 

 lined with epithelium, and are penetrated at their 

 extremities by bloodvessels which form coils or 



Fig. 241. Postal pig | of -*!* TU A u*. Ji 



an inch (16 millimeters) long, convolutions in their interior. These undoubtedly 

 From^a specimen prepared by ^ Q organs o f depuration for the embryo and take 



on the office to be afterward assumed by the 



i, heart; 2, anterior ex- J 



tremity; 3, posterior ex- kidney s ; but in the female they are temporary 

 ^^S2^U. structures, disappearing as development advances 



been cut away in order to and having nothing whatever to do with the de- 

 show the position of the , r , . / -p,, , 



Wolffian bodies. velopment of the true urinary organs (see Plate 



XV, Fig. 6). 



The testicles or ovaries are developed at the internal and anterior 

 surface of the Wolffian bodies, first appearing in the form of small ovoid 

 masses. Beginning just above and passing along the external borders 

 of the Wolffian bodies, are the tubes called the ducts of M-iiller. These 

 at first open into the intestine near the point of entrance of the Wolffian 

 ducts. In the female their upper extremities remain free, except the 

 single fimbria which is connected with the ovary. Their inferior 

 extremities unite with each other, and at their point of union they form 

 the uterus. The Wolffian bodies and their ducts disappear in the female 

 at about the fiftieth day. A portion of their structure, however, persists 

 in the form of a collection of closed tubes constituting the parovarium, 

 or organ of Rosenmiiller. 



In the female the ovaries pass down no farther than the pelvic cavity ; 



