224 MICROSCOPIC ANATOMY OF THE ORGAXX. 



fibres, separated by connective tissue containing elastic fibres. 

 Outside the circular coat, especially in the upper part of the 

 canal, are strands of striated muscle fibres, forming the mus- 

 culus compressor urethra. The iiiucosa is supplied richly with 

 blood-vessels, of which the veins form a thick plexus in the 

 submucosa. 



V. GENERATIVE (REPRODUCTIVE) SYSTEM. 



1. MALE SEXUAL ORGANS. 



A. Testes. 



The testes are branched tubular glands. The whole organ 

 is surrounded by a fibrous capsule, the so-called tunica albu- 

 ginea s. fibrosa, which consists of firm connective tissue. The 

 outer surface of this is attached closely to the visceral layer of 

 the tunica vaginalis propria (tunica adnata). Both the visceral 

 and parietal layers form a process of the peritoneum, and 

 enclose between them a space which is a part of the body 

 cavity. They are thin connective-tissue membranes with a 

 layer of flat epithelium covering the free surface. Between the 

 visceral layer of the tunica vaginalis propria and the next layer, 

 the tunica vaginalis communis, there is a layer of smooth muscle 

 cells which form the internal cremaster muscle (Fig. 174). 



Toward the inside the tunica albuginea borders on a sheath 

 of loose connective tissue, which, on account of its richness in 

 blood, is called the tunica vasculosa. This rests directly on the 

 parenchyma of the testis. 



In the posterior upper part of the testis there lies a collec- 

 tion of firm connective tissue in the form of an oval hillock. 

 This is the so-called mediastinum testis or corpus Highmori. 

 From it there are sent, in a radiating direction, into the organ 

 many bands of connective tissue, the septula testis. These pass 

 through the testis as far as the tunica vasculosa, and at the 

 same time divide the organ into lobules (lobuli testis), which 

 have the form of pyramids with their bases toward the outside 

 and their apices toward the centre of the organ (Fig. 174). 



The whole of the parenchyma contained in a lobule consists 



