1206 



SPLANCHNOLOGY 





1107). By the fifth or sixth week this body forms an elongated spindle-shaped 

 structure, termed the urogenital fold (Fig. 1106), which projects into the celomic 

 cavity at the side of the dorsal mesentery, reaching from the septum transversum 

 in front to the fifth lumbar segment behind; in this fold the reproductive glands are 

 developed. The Wolffian bodies persist and form the permanent kidneys in fishes 

 and amphibians, but in reptiles, birds, and mammals, they atrophy and for the 

 most part disappear coincidently with the development of the permanent kidneys. 

 The atrophy begins during the sixth or seventh week and rapidly proceeds, so that 

 by the beginning of the fifth month only the ducts and a few of the tubules remain. 



In the male the Wolffian duct persists, 

 and forms the tube of the epididymis, the 

 ductus deferens and the ejaculatory duct, 

 while the seminal vesicle arises during the 

 third month as a lateral diverticulum from 

 its hinder end. A large part of the head 

 end of the mesonephros atrophies and dis- 

 appears; of the remainder the anterior 

 tubules form the efferent ducts of the 

 testis; \vhile the posterior tubules are 

 represented by the ductuli aberrantes, 

 and by the paradidymis, which is some- 

 times found in front of the spermatic 

 cord above the head of the epididymis 

 (Fig. 1110, C). 



In the female the Wolffian bodies and ducts atrophy. The remains of the 

 Wolffian tubules are represented by the epobphoron or organ of Rosenmiiller, and 

 the paroophoron, two small collections of rudimentary blind tubules which are 

 situated in the mesosalpinx (Fig. 1108). The lower part of the Wolffian duct 

 disappears, while the upper part persists as the longitudinal duct of the epoophoron 

 or duct of Gartner 1 (Fig. 1110, B). 



FIG. 1107. Enlarged view from the front of the 

 left Wolffian body before the establishment of the 

 distinction of sex. (From Farre, after Kobelt.) o, 

 a, b, c, d. Tubular structure of the Wolffian body. 

 e. Wolffian duct. /. Its upper extremity, g. Its 

 termination in x, the urogenital sinus, h. The duct 

 of Miiller. i. Its upper, funnel-shaped extremity. 

 k. Its lower end, terminating in the urogenital sinus. 

 I. The genital gland. 



FIG. 1108. Broad ligament of adult, showing epoophoron. (From Farre, after Kobelt.) a, a. Epoophoron formed 

 from the upper part of the Wolffian body. b. Remains of the uppermost tubes sometimes forming appendices, c. Middle 

 set of tubes, d. Some lower atrophied tubes, e. Atrophied remains of the Wolffian duct. /. The terminal bulb or 

 hydatid. h. The uterine tube, originally the duct of Muller.- t. Appendix attached to the extremity. 7. The ovary. 



The Miillerian Ducts. Shortly after the formation of the Wolffian ducts a 

 second pair of ducts is developed; these are named the Miillerian ducts. Each 

 arises on the lateral aspect of the corresponding Wolffian duct as a tubular invag- 



1 Berry Hart (op. cit.) has described the Wolffian ducts as ending at the site of the future hymen in bulbous enlarge- 

 ments, which he has named the Wolffian bulbs; and states that the hymen is formed by these bulbs, "aided by a special 

 involution from below of the cells lining the urogenital sinus. " He further believes that "the lower third of the vagina 

 is due to the coalescence of the upper portion of the urogenital sinus and the lower ends of the Wolffian ducts, and 

 that "the epithelial lining of the vagina is derived from the Wolffian bulbs. " He also regards the colliculus semmalis 

 of the male urethra as being formed from the lower part of the Wolffian ducts. 



