MALE REPRODUCTIVE SYSTEM OF MAMMALS 247 



the vas (IctVrcns. Within the iuhentitia is a tliiii niuseularis coat 

 with an outer loiijiitudinal sheath. The tunica i)r()j)ria of loose 

 connective tissue su])i)orts an e})ithehuni of siin])le eohunnar epithe- 

 hum or of cells of the same tyj)e as the vas deferens, i. e., stratified 

 columnar. Any cross-section reveals many com))li('ated ])assages 

 and s])aces set off from each other. (Fig. 152.) This is because the 

 mucous membrane is elal)orately folded and in i)laces the folds have 

 fused to form a complex system of labyrinthine passages within 

 the lumen. The seminal ^'esicles probably do not store sperm but 

 su])])ly a secretion which is added to the sperm fluid proper after 

 the latter enters the urethra at the time of discharge. The lumen 

 is usually filled with an acidophilic colloidal material. 



Fig. 153. — Photograph of a cross-section of the dog's prostate, showing .5 glandular 

 masses opening into the urethra by excretory du.f'ts. 



The Prostate. — The prostate is a glandular mass, roughly spherical 

 in shajie, which surroimds the male lU'ethra just distal to its origin 

 from the bladder. (Fig. loo.) Within the ])rostatic mass are a 

 number of small glands of the compound tubular and alveolar type. 

 There are a number of ducts from these glands entering the urethra. 

 Around the whole ])r()static mass is a capsule of fibroelastic connec- 

 tive tissue which has extensions within the mass between adjacent 

 glandular structures. The epithelium lining the glands varies from 

 cuboidal to columnar. In the connective tissue between the 

 glandular ])ortions are patches of smooth muscle cells indicating 

 that the mass may contract and force its secretions into the urethra. 

 The secretion is a thin, whitish fluid and forms the bulk of the 

 spermatic fluid. Sometimes spherical masses of ^'ar^•ing size with 

 concentric lamelhie occur in the lumens of the glands. 



