THE EPIDIDYMIS. 



1947 



vested by a delicate envelope, with the exception of the last .004 .006 mm. that con- 

 tinues uncovered as the attenuated end-piece. In front, minute spherical thickenings, 

 the neck-granules, mark the termination of the axial fibre, where it joins, but does 

 not penetrate, the head. They probably represent the centrosome of the spermatid. 

 Within the middle-piece the envelope surrounding the axial fibre, after the action 

 of certain stains, exhibits markings that suggest the presence of a spirally arranged 

 filament of great delicacy. 



THE EPIDIDYMIS. 



The epididymis, the greatly convoluted beginning of the seminal duct, is a 

 crescentic body, triangular in section, that covers the entire posterior border and the 

 adjacent part of the outer surface of the testis. Its enlarged upper end or globus 

 major (caput epididymidis) covers the superior pole of the sexual gland and is attached 

 to the latter not only by connective tissue and serous membrane (as is the globus 

 minor), but by the efferent ducts that establish communication between the testis and 

 its excretory canal. The succeeding part, the body, gradually tapers as it descends to 

 the lower pole, at which point the epididymis presents a second and less conspicuous 

 enlargement, the globus minor (cauda epididymidis), that bends backward to become 

 the vas deferens. The latter passes 



upward along the median side of F IG - l6 59- 



the posterior border of the epidid- 

 ymis to ascend in the spermatic 

 cord. Where attached to sur- 

 rounding structures, as at its two 

 ends where in contact with the tes- 

 ticle and along its posterior border 

 where blended with the spermatic 

 cord, the epididymis is devoid of 

 serous covering ; in other places 

 it is completely invested by the 

 tunica vaginalis, a deep recess, the 

 digital fossa (sinus epididymidis) 

 intervening between the body of 

 the epididymis and the adjacent 

 surface of the testis. The bulk of 

 the globus major depends upon 

 the aggregation of from twelve to 

 fifteen conical masses (lobuli epi- 

 didymidis) formed by the efferent 

 ducts and their tortuosities, the 

 coni vasculosi, that pass from the 

 upper end of the testis and connect 

 the rete testis with the canal of 

 the epididymis. 



The latter (ductus epididymi- 

 dis), beginning in the globus major, receives the efferent ducts and becomes greatly 

 convoluted, the extraordinary windings of the single tube contributing the chief bulk 

 of the body and the tail of the epididymis. When unravelled, the canal measures 

 from 5-5.5 m. (18-20 ft. ) in length, its remarkable convolutions sufficing to pack 

 away this long duct within the small volume of the epididymis. 



Structure. The conical lobules of the globus major are enclosed by a fibrous 

 envelope resembling but less robust than the tunica albuginea testis, within which the 

 convolutions of a single tubule are held together by delicate vascular connective tissue. 

 The transition of the channels of the rete testis into the efferent ducts is marked by 

 an abrupt change in the character of the lining epithelium, the low cuboidal cells of 

 the former giving place to irregularly ciliated columnar elements within the latter. 

 The tubules from .2-. 5 mm. in diameter present an irregular lumen, owing to the 

 inconstant thickness and pitted surface of their epithelium. Just before terminating 



Globu 

 mino 



Pyramidal lobules of gland-tissue (seminiferous tubules) 



Dissection of testicle after tubules have been filled with quick- 

 silver ; testis has been separated into the component lobules. 



