THE TESTES. 



1157 



Spermatic cord. 



Artery of 

 cord. 



Tunica raginalis, 

 parietal layer. 



The parietal portion of the serous membrane (tunica vaginalis refiexa) is far 

 more extensive than the visceral portion, extending upward for some distance in 

 front and on the inner side of the cord, and reaching below the testis. The inner 

 surface of the tunica vaginalis is free, smooth, and covered by a layer of endothelial 

 cells. The interval between the visceral and parietal layers of this membrane 

 constitutes the cavity of the tunica vaginalis. 



The obliterated portion of the pouch may generally be seen as a fibro-cellular 

 thread lying in the loose areolar tissue around the spermatic cord; sometimes this 

 may be traced as a distinct band from the upper end of the inguinal canal, where 

 ir is connected with the peritoneum, down to the tunica vaginalis; sometimes it 

 gradual] v becomes lost on the spermatic cord. 

 Occasionally no trace of it can be detected. In 

 some cases it happens that the pouch of peri- 

 toneum does not become obliterated, but the sac 

 of the peritoneum communicates with the tunica 

 vaginalis. This may give rise to one of the 

 varieties of oblique inguinal hernia (page 1191). 

 Or in other cases the pouch may contract, but 

 not become entirely obliterated ; it then forms 

 a minute canal leading from the peritoneum to 

 the tunica vaginalis, 1 



The Tunica Albuginea is the fibrous cover- 

 ing of the testis. It is a dense fibrous mem- 

 brane, of a bluish-white color, composed of 

 bundles of white fibrous tissue, which interlace 

 in every direction. Its outer surface is covered 

 by the tunica vaginalis, except along its poste- 

 rior border, at the points of attachment of the 

 epididymis : hence the tunica albuginea may 

 be considered as a fibro-serous membrane, 

 like the pericardium. This membrane sur- 

 rounds the glandular structure of the testicle, 

 and at its posterior border is reflected into the interior of the gland, forming an 

 incomplete vertical septum, called the mediastinum testis (corpus Hiyhmorianuni). 



The mediastinum testis extends from, the upper, nearly to the lower, border of 

 the gland, and is wider above than below. From the front and sides of this septum 

 numerous slender fibrous cords and imperfect septa (trabeculae) are given off, which 

 radiate toward the surface of the organ, and are attached to the inner surface of 

 the tunica albuginea. They therefore divide the interior of the organ into a 

 number of incomplete spaces, which are somewhat cone-shaped, being broad at 

 their bases at the surface of the gland, and becoming narrower as they converge to 

 the mediastinum. The mediastinum supports the vessels and ducts of the testis 

 in their passage to and from the substance of the gland. 



The Tunica Vasculosa ( pi a mnffr testis) is the vascular layer of the testis, 

 consisting of a plexus of blood-vessels held together by a delicate areolar tissue. 

 It covers the inner surface of the tunica albuginea and the different septa in the 

 interior of the gland, and therefore forms an internal investment to all the spaces 

 of which the gland is composed. 



Structure. The glandular structure of the testis consists of numerous lobules 

 (lobnl! tt'*tfx). Their number, in a single testis, is estimated by Berres at 250, and 

 by Krause at 400. They differ in size according to their position, those in the 

 middle of the gland being larger and longer. The lobules are conical in shape, 

 the base being directed toward the circumference of the organ, the apex toward the 



1 It is recorded that in the post-mortem examination of Sir Astley Cooper this minute canal 

 was found on botli sides of the body. Sir Astley Cooper states that when a student he suffered from 

 inguinal hernia ; probably this was of the congenital variety, and the canal found after death was the 

 remains of the one down which the hernia travelled (Lancet, vol. ii., 1824, p. 116). 



FIG. 739. The testis in fitu, the tunica 

 vaginalis having been laid open. 



