PROSTATE. 28l 



it together with the ejaculatory ducts and the prostatic utricle. The 

 prostatic urethra is embryologically the neck of the bladder, and as the 

 glands grow out they become surrounded by the smooth muscle fibers 

 of the bladder or urethra. The smooth muscle of the adult prostate forms 

 a quarter of the bulk of the organ, and together with an elastic connec- 

 tive tissue it unites the numerous glands in a compact mass. 



The glandular epithelium is simple and either cuboidal or columnar. 

 It may appear stratified as it passes over the folds in the walls of the tubules. 

 Xear the outlet of the larger ducts the epithelium is like that of the 

 bladder and prostatic urethra. In the 



, i i r i i Smooth Connective 



prostatic alveoli, of older persons espe- muscle. Glands. tissue. 



ciallv, round or oval colloid masses |\ 



J ' A ,.-,,.,,-,..,,.._-] A_ 



g? 



r i- 



from 0.3 to i.o mm. in diameter occur; 

 as seen in sections (Fig. 321) they 

 exhibit concentric layers. Their re- 

 actions on treatment with iodine solu- 

 tions suggest amyloid. These concre- 

 tions are probably deposited around frag- 

 ments of cells. Octahedral crystals also 

 occur in the prostatic secretion, which 

 is a thin milky emulsion, faintly acid; it 

 has a characteristic odor which is ab- 

 sent from the other constituents of the 

 seminal fluid. ^,., 



The smooth muscle fibers are 

 found everywhere between the pros- 

 tatic lobules; toward the urethra they 

 thicken to form the internal sphincter of 

 the bladder. Smooth muscle is also 



abundant On the Surface Of the prOState FIG. 320. FROM A SECTION- OF THE PROS- 

 TATE OP A MAN TWENTY-THREE YEARS 



and it borders upon the striated fibers LD - x so. 



of the sphincter of the membranous 



urethra. The prostate is abundantly supplied with blood and lymph 



vessels. The numerous nerves form ganglionated plexuses from which 



non-medulla ted fibers pass to the smooth muscles; others of the nerves 



have free endings; still others, both in the outer and inner parts of the 



gland in dogs and cats, end in cylindrical lamellar corpuscles. 



URETHRA AND PENIS. 



The form of epithelium found in the bladder extends through the 

 prostatic to the membranous part of the urethra. Its outer cells grad- 



