THE URINOGENITAL ORGANS 



connected with the peritoneum, down to the tunica vaginalis; sometimes it gradu- 

 ally becomes lost on the spermatic cord. Occasionally no trace of it can be de- 

 tected. In some cases it happens that the pouch of peritoneum does not become 

 obliterated, but the peritoneal cavity communicates with the tunica vaginalis. 

 This may give rise to one of the varieties of oblique inguinal hernia or hydrocele; 

 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. 



The tunica albuginea (Figs. 1131 and 1132) is the fibrous covering of the testis. 

 It is a dense fibrous membrane, 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 at the points of attachment of the epididy- 

 mis to the testis, and along its posterior border, where the spermatic vessels enter 

 the gland. It consists of two portions, the tunica fibrosa and the tunica vasculosa ; 

 the former is the thicker of the two and contains few vessels, while the latter con- 

 tains many small vessels. The tunica vasculosa sends septa into the organ 

 which divide it into compartments. These septa converge and end at the 

 mediastinum. This membrane surrounds the glandular structure of the testis, 

 and at its posterior border forms a projection, triangular in shape and cellular 

 in structure, which is reflected into the interior of the gland, forming an incomplete 

 vertical septum, called the mediastinum testis. 



The mediastinum testis (corpus Highmori) (Figs. 1131 and 1132) extends 

 from the upper, nearly to the lower, extremity of the gland, and is wider above 

 than below. From the front and sides of this septum numerous slender fibrous 

 cords and imperfect septa septiUa te'stis (Fig. 1132) are given off, which radiate 

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

 albuginea. This scaffolding of connective tissue divides the parenchyma (paren- 

 chyma testis) 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 bloodvessels, lymphatics, and ducts of the testis in their passage to and from 

 the substance of the gland, and contains numerous fine canals, into which open 

 the very small tubules of the proper substance of the testis. 



Structure of the Testis (Fig. 1132). -The glandular structure of the testis consists of 

 numerous lobules (lobuli testis). Their number, in a single testis, is estimated to be about 200. 

 They differ in size according to their position, those in the middle of the gland being larger and 

 longer. The lobules are pyramidal in shape, the base of each being directed toward the circum- 

 ference of the organ, the apex toward the mediastinum. Each lobule is contained in one of the 

 intervals between the fibrous cords and vascular processes which extend between the medias- 

 tinum testis and the tunica albuginea, and consists of from one to three or more minute convo- 

 luted tubes 2i feet in length and 140 to 200 ft in diameter, the tubuli seminiferi contort!, which 

 usually end blindly beneath the tunica albuginea. The contorted tubes unite at the apex of 

 the lobules and form several straight tubes (tubuli recti), which pass into the mediastinum testis 

 and form the network known as the rete testis (Fig. 1132). The efferent ducts (ductuli e/er- 

 entes testis) (Fig. 1132), about twelve to fifteen in number, arise from the rete and continue into 

 the globus major as the coni vasculosi. The total number of tubes is considered by Lauth to 

 be about 840. The tubuli recti and rete testes are lined by simple squamous or cuboidal cells, 

 while the vasa efferentia are lined by simple columnar cells which are either ciliated or non- 

 cihated. The convoluted tubules are pale in color in early life, but in old age they acquire a 

 deep yellow tinge from containing much fatty matter. Each tube consists of a basement layer, 

 formed of epithelial cells united edge to edge, outside of which are other layers of flattened cells 

 arranged in interrupted laminae, which give to the tube an appearance of striation in cross- 

 The cells of the outer layers gradually pass into the interstitial tissue. Within the base- 

 ment membrane are epithelial cells arranged in several irregular layers, which are not always 

 clearly separated, but which may be arranged in different groups that do not form clearly defined 

 layers. The various groups cannot be seen in a single cross-section, but may be discerned in 

 successive sections. Among these cells may be seen the spermia in different stages of develop- 

 ment. (1) Lining the basement membrane and forming the outer zone is a layer of cubical 

 cells, spermatogonia, containing small nuclei and pyramidal cells, the columns of Sertoli. The 



