380 THE GENITO-URINARY SYSTEM 



the skin covering these two surfaces only becomes continuous 

 at the base of the glans and at the frenulum. It often happens, 

 however, that the two opposed surfaces remain adherent to 

 one another in some areas. Such adhesions are capable of 

 producing reflex symptoms, which may vary from enuresis to 

 symptoms closely resembling vesical calculus. The areas of 

 skin involved are supplied by the dorsal nerves of the penis 

 (S. 2, 3 and 4) (p. 184), and it would appear that the adhesions 

 affect their terminal fibres in some way so as to set up a 

 "focus of irritation" (p. 195) within the mid-sacral region of 

 the spinal medulla. This portion of the spinal medulla is 

 accustomed to receive impulses from the internal trigone of 

 the bladder (p. 368), including the ordinary impulses which 

 are interpreted in the cortex as a desire to micturate. The 

 establishment of a " focus of irritation " in this situation will, 

 if sufficiently strong, produce symptoms identical with those 

 in which the internal trigone is irritated by the presence of a 

 vesical calculus. Why such simple adhesions should be 

 capable of causing such violent reflexes has not yet been 

 explained satisfactorily. Simple division of the adhesions 

 removes all the symptoms. 



DEVELOPMENT OF THE EPIDIDYMIS, DUCTUS DEFERENS 

 AND TESTIS. The development of these three structures is 

 intimately associated with the presence of the transitory 

 Wolffian body during early foetal life. 



The Wolffian Body, or primitive kidney, is an elongated 

 gland which lies on the posterior abdominal wall. It possesses 

 a longitudinal duct which opens, at its caudal extremity, into 

 the ventral portion of the cloaca (p. 369). 



The reproductive gland, which at first possesses no sexual 

 characteristics, lies on the ventral aspect of the Wolffian body. 

 In the male, it becomes differentiated into the testis, and its 

 tubules gain a connexion with the Wolffian Duct, as the 

 Wolffian body atrophies. This connexion persists and the 

 cephalad portion of the duct develops into the epididymis, 

 while its caudal portion becomes the ductus deferens. 



