1272 



PHYSIOLOGY 



back of the testis. The epididymis is composed of the convolutions of this 

 single duct, which is about 20 feet long. From the lower end of the epi- 

 didymis the vas deferens, a tube with thick muscular walls, leads by the 

 abdominal ring to the base of the bladder, where it opens into the beginning 

 of the urethra in its prostatic part. Just before it joins the urethra each va^ 

 deferens presents a diverticulum, the seminal vesicle, which lies along, and 

 is attached to, the base of the bladder. The prostate itself, which surrounds 

 the first part of the urethra, is composed of a matrix of unstriated muscular 

 fibres, enclosing numerous branched racemo-tubular glands. From the 

 point of entry of the vasa deferentia to its orifice, the urethra represents 



Appendix 



Epididymis 



Tunica vaginalis 



Tunica albnginea 



Septum 



Seminal tubules 



Lobule 

 Mediastinum 



Testis 



, Vas deferens 



Paradidymis 



Vasa efferentia 



Appendix of rete 

 testis 



Vas aberrans 



Lobule Straight Eete 

 tubules testis 



FIG. 573. Diagrammatic representation of the course of the seminal tubules in the 

 testis and epididymis. (After NAGEL.) 



a common passage for the urine and for the sexual products the semen. 

 It passes therefore through tissues, forming the penis, which are especially 

 adapted for the purpose of intromission, i. e. the introduction of the semen 

 containing the spermatozoa into the female. In the urethra we .distinguish 

 the prostatic, the membranous, and the penile portions. Into the beginning 

 of the penile portion, the bulb of the urethra, open the ducts of the two 

 glands of Cowper. In the penis itself the urethra is surrounded with 

 erectile tissue, forming the corpus spongiosum, and lies between the two 

 corpora cavernosa, which consist of the same kind of tissue. The erectile 

 tissue is a spongy meshwork of elastic and unstriated muscle fibres, enclosing 

 spaces in free communication with the efferent veins of the organ. The 

 arterioles also open into Ilicse spaces, but under normal circumstances both 

 the arterioles and the muscle tissues of the framework are contracted, so 

 that the blood trickles very slowly from the arterioles into the spaces, 

 whence it escapes readily by means of the veins. Tf the muscle fibres !)< 



