136 NOKMAL HISTOLOGY. 



sion of the capsule a much thickened mass, the mediastinum, or 

 corpus Highrnori; and the tunica vasculosa, containing a plexus of 

 blood-vessels invested by delicate areolar tissue. The septa, which 

 extend from the mediastinum to the tunica albuginea on the oppo- 

 site side, thus dividing the testis into lobules, are continuous with 

 tunica vasculosa. Each lobule is composed of tubules of three kinds 

 convoluted tubules, tubuli recti, and those of the rete testis. The 

 convoluted tubule consists of a basement membrane lined with the 

 sustentacular cells, or parietal layer. Just within this layer are the 

 mother cells, which grow into large cells and multiply by mitosis. 

 Then follow the daughter cells, or spermatoblasts. Within these 

 are to be found the spermatozoa. These tubules are supported by 

 connective tissue derived from the septa, arc provided with blind 

 extremities, and each has a membrana propria. The tubuli recti 

 comprise the straight tubules formed by the union of the convoluted 

 tubules near the apex of the pyramidal lobule, and possess a base- 

 ment membrane lined with columnar cells. The rete testis consists 

 of anastomosing tubules forming a network within the mediastinum. 



The vessels, or ducts, associated with the tubules are the vasa ef- 

 ferentia, coni vasculosi, epididymis, vas deferens, and vas aberrans. 

 The tubules of the rete testis emerge from the mediastinum in fif- 

 teen or twenty ducts, the vasa efferentia. These soon become con- 

 voluted in their course, forming conical masses, the coni vasculosi, 

 which together constitute the head of the epididymis, or globus 

 major. The tube of the epididymis is formed by the union of the 

 ducts of the coni vasculosi. This tube is greatly convoluted, and 

 when unraveled measures upward of twenty feet. The vas aber- 

 rans is a narrow tube, which extends from the lower part of the 

 tube of the epididymis and is closed by a blind extremity. The vas 

 deferens is continuous with the epididymis, and is the excretory duct 

 of the testis. It consists of three coats epithelial, muscular, and 

 mucous. 



THE PROSTATE GLAND. This is composed largely of 

 smooth muscle, within which are a number of tubular glands, whose 

 ducts open into the urethra. The fibrous capsule is thin, but firm. 



COWPER'S GLANDS. These are two in number, and in 



