480 



DISSECTION OF THE ABDOMEN. 



and the vessels of the latter are to be followed to their entrance into the 

 testicle. 



The tunica vaginalis (fig. 168, d) is a serous bag, which is continuous 

 in the foetus with the peritoneal lining ot the abdomen, but becomes subse- 

 quently a distinct sac through the obliteration of the part connecting the two. 

 It invests the testicle after the manner of other serous membranes : 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 secerning smooth surface ; 

 and like them it has a visceral and a parietal 

 part. To examine its disposition the sac should 

 be opened. 



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 forms a pouch be- 

 tween the testis and the arched body (epididymis) 

 on this aspect of the organ. 



The parietal part of the sac (tunic, vagin. 

 scroti) is more extensive than the piece covering 

 the testicle, and lines the contiguous layer of the 

 scrotum. 



Form and position of the testis (fig. 168). 

 The testicle is oval in shape, with a smooth sur- 

 face, and is flattened on the sides. The ante- 

 rior, which is flattened, is pierced by the sperma- 

 tic vessels and nerves. Stretching like an arch 

 along the outer part is the epididymis (). At- 

 tached to the upper end of the testis is a small 

 body (c) two or three lines in length (corpus 

 Morgagni), which is the remains of the upper 

 end of the foetal duct of Muller ; 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 nearly an ounce, and the left is frequently larger than the 

 other. 



STRUCTURE. The substance of the testicle is composed of minute se- 

 cerning tubes, around which the bloodvessels are disposed in plexuses. 

 Surrounding and supporting the delicate seminiferal tubes is a dense 

 covering the tunica albuginea. Its excretory or efferent duct is named, 

 vas deferens, 



Dissection. With the view of examining the investing fibrous coat, let 

 the testis be placed on its outer side, viz., that on which the epididymis 



THE TESTIS WITH THE TUNICA 

 VAGINALIS LAID OPEN. 



a. Testicle. 



b. Head of the epididymis. 



c. Corpus Morgagni. 



d. Parietal part of the tunica 



vaginalis. 



e. Vessels of the spermatic 



cord 

 /. Vas deferens. 



