420 TEXT-BOOK OF EMBRYOLOGY. 



miiller) which comes to lie in the mesosalpinx between the oviduct and the 

 mesovarium, and later in the mesentery between the oviduct and the ovary 

 (Fig. 373). At the height of their development the tubules are lined with 

 columnar, ciliated epithelium. The rete cords of the ovary (rete ovarii, p. 410) 

 during their development unite with the tubules in the cephalic portion of the 

 mesonephros, but later disappear. The epoophoron is homologous with the 

 tubules of the head of the epididymis in the male. 



The caudal portion of the mesonephros leaves a ^ew tubular remnants 

 which come to lie in the broad ligament near the hilus of the ovary. These con- 

 stitute the paroophoron \vhich is homologous with the paradidymis in the male 

 (Fig. 373). They may disappear before birth or may persist through life. 



The mesonephric duct also leaves certain remnants which are situated (i) in 

 the broad ligament, (2) in the lateral wall of the uterus, (3) in the lateral wall of the 

 vagina, and (4) in the tissue lateral to the external genital opening. These rem- 

 nants are known as the canals of Gartner, and they naturally lie in the course of 

 the duct in the embryo. All the rudimentary structures derived from the 

 mesonephroi and their ducts are extremely variable. 



In the Male. In the male all the efferent ducts of the genital glands, except 

 the rete testis, are derived from the mesonephroi and their ducts. As described 

 earlier in this chapter (p. 414), the rete testis acquires a connection with some of 

 the tubules in the cephalic end of the mesonephros and with the sex cords or 

 anlagen of the convoluted and straight seminiferous tubules (see Fig. 365). 

 This establishes a communication between the seminiferous tubules and the 

 tubules of the mesonephros. Those mesonephric tubules with which the rete 

 testis unites persist as the efferent ductules (or vasa eff erentia) . The latter form 

 a set of coiled ducts which are situated in the head of the epididymis and which 

 open into the cephalic part of the mesonephric duct (Fig. 347). They are 

 homologous with the epoophoron in the female. 



The next succeeding portion of the mesonephric duct becomes the duct of the 

 epididymis which in its tortuous course constitutes the bulk of the body and tail 

 of the epididymis and passes over into the caudal portion of the mesonephric 

 duct. The latter portion becomes the deferent duct (vas def erens) . The caudal 

 end of the deferent duct forms the ejaculatory duct which opens into the urogeni- 

 tal sinus. The seminal vesicles appear during the third month as lateral 

 evaginations from the ejaculatory ducts. 



The portions of the mesonephros not involved in the formation of the duct 

 system of the testicle atrophy and for the most part disappear. They leave 

 certain tubules, however, which persist as rudimentary structures connected 

 with the testicle. In the cephalic end, some of the tubules persist in part and 

 come to lie among the efferent ductules, being either attached to the latter or un- 

 connected, and forming the appendage of the epididymis. The caudal part of 



