278 



DISSECTION OF THE ABDOMEN. 



To see the 

 serous sac. 



Tunica 

 vaginalis 



partly 

 covers the 

 testicle, 



and lines 

 scrotum : 



visceral 

 part, 



and parietal. 



Testicle 

 oval ; 



margins. 

 Epididymis. 



Hydatid of 

 Morgagni. 



Suspended 

 obliquely. 



Dimensions 

 and weight. 



A dense 

 tunic en- 

 closes small 

 secreting 

 tubes. 



each is provided with an excretory duct named the vas deferens. A 

 serous sac partly surrounds each organ. 



Dissection. For the purpose of examining the serous covering of 

 the testicle (tunica vaginalis) make a small aperture into the upper part 

 of the sac when the skin of the scrotum and the superficial coverings 

 have been reflected and inflate it. The sac and the spermatic 

 cord are then to be cleaned ; and the vessels of the latter are to be 

 followed to their entrance into the testicle. Finally the tunica 

 vaginalis is to be opened from the front to expose the testis. 



The tunica vaginalis (fig. 103, d} is a serous bag, which is con- 

 tinuous in the foetus with the peritoneal lining of the abdomen, but 

 becomes subsequently a distinct sac through the obliteration of the 

 intermediate part. 



It invests the testicle after the manner of other serous mem- 

 branes ; for the testicle is placed behind it, so as to be partly 

 enveloped by it. The sac, however, is larger than is necessary for 

 covering the testicle, and projects some distance above it. Like 

 other serous membranes, it has an external rough, and an internal 

 smooth surface ; and like them, it has a visceral and a parietal part. 



The visceral layer (tunica vaginalis testis) covers the testicle, except 

 posteriorly where the vessels lie. On the outer side it extends 

 farther back than on the inner, and invests the greater part of the 

 epididymis, forming a pouch (digital fossa) between that body and 

 the testicle. 



The parietal part of the sac (tunica vaginalis scroti) is more 

 extensive than the piece covering the testicle, and lines the con- 

 tiguous layer of the scrotum. 



Form and position of the testis (fig 103). The testicle is oval in 

 shape, with a smooth surface, and is somewhat compressed from side 

 to side. The anterior margin is convex and free ; the posterior, 

 is flattened, and is pierced by the spermatic vessels and nerves. 

 Stretching like an arch along the outer side is the epididymis (6). 

 Attached to the upper end of the testis is a small body (c), the 

 hydatid of Morgagni, which is the remains of the upper end of the 

 foetal duct of Miiller ; and occasionally other smaller projections of 

 the tunica vaginalis are connected with the top of the epididymis. 



The testis is suspended obliquely, so that the upper part is directed 

 forwards and somewhat outwards, and the lower end backwards and 

 rather inwards. 



Size and weight. The length of the testis is an inch and a half 

 or two inches ; from before backwards it measures rather more 

 than an inch, and from side to side rather less than an inch. Its 

 weight is nearly an ounce, and the left is frequently larger than the 

 other. 



STRUCTURE. The substance of the testicle is composed of minute 

 secreting tubes, around which the blood-vessels are disposed in 

 plexuses. Surrounding and supporting the delicate seminiferous 

 tubes is a dense covering the tunica albuginea. The excretory, or 

 efferent, duct is the vas deferens. 



