THE PROSTATE GLAND. 



1977 



Fig. 1682. 



Terminal duct opening into alveoli 

 Involuntary muscle^ ^J^^Gf' 



Interlobular 

 connective 



tissue 



attached to the lower surface of the bladder, lying beneath the vesical trigone. 

 Below, its apex rests upon the superior layer of the triangular ligament, surrounded 

 by fibres of the compressor urethrse muscle that constitute the external vesical 

 sphincter (page 1925). In front, the, rounded anterior surface is directed towards 

 the pubic symphysis, from which it is separated by an intervening wedge-shaped 

 space occupied by loose areolar tissue containing part of the prostatic plexus of veins 

 and fat. The pubo-prostatic ligaments (the continuations of the arcus tendineus of 

 the two sides) stretch between the symphysis and the prostate and contain muscular 

 tissue prolonged from the latter and the bladder. At the sides, the prostate is embraced 

 by the levator ani muscles, the prostatic venous plexuses, embedded within the 

 reflections of the pelvic fascia that here constitute the capsule of the gland, inter- 

 vening. Behind, the prostate is in relation with the ampullae of the vasa deferentia 

 and the seminal \:esicles abo\'e and with the lower part of the rectum below, separated 

 from the latter by the dense capsule and the overlying layer of areolar tissue. The 

 position of the prostate is not constant, since it is affected by movements of the vesi- 

 cal wall, with which the prostate is intimately united, incident to marked distention 

 and contraction of 

 the bladder. On the 

 other hand, the at- 

 tachments of the 

 prostate to the trian- 

 gular ligament and 

 pelvic fascia indi- 

 rectly confer upon 

 the lower segment of 

 the bladder its most 

 efficient means of 

 fixation. The pros- 

 tate is further influ- 

 enced by changes in 

 the anterior wall of 

 the rectum, under- 

 going compression 

 and displacement 

 forward when the 

 bowel is distended. 



Structure. — 

 The prostate is a 

 gland of the tubo- 

 alveolar type and is 

 made up "of three 



chief components, -^the connective-tissue framework, involuntary muscle, and the glan- 

 dular tissue. Of these the latter constitutes usually a litde more than one-half of the 

 entire organ, and the connective tissue and muscle each somewhat less than one-quarter. 



The zonViftQVw^-'d'S'iWft framework consists of an external investing fibro-elastic en- 

 velope, the capszile proper, and a median septum, which encloses and blends with the 

 walls of the urethra. Between these denser lamellae numerous partitions radiate and 

 subdivide the organ into from thirty to forty pyramidal lobules occupied by the glandu- 

 lar tissue. The itivoluntary nmscle, embedded within the capsule and ramifications 

 of the connective-tissue framework, surrounds the gland-substance as a superficial 

 layer from which a median septum, about 2 mm. in width, extends ventro-dorsally, 

 enclosing the urethra in an annular thickening. In consequence, the interior of the 

 prostate is occupied by a dense fibro-muscular micleus, in which the glandular tissue 

 is represented by only the narrow prostatic ducts passing towards the urethra. The 

 muscle is not lirnited, however, to the foregoing positions, but extends also between 

 the ultimate divisions of the gland-tissue, the interalveolar septa in places consisting 

 largely of the variously disposed muscle-bundles. 



The gland^dar tissiie consists of twenty or more distinct tube-systems, each 

 drained by an independent duct that opens into the urethra in the groove on either side 



Alveoli 



Blood-vessel 



Portion of cross-section of prostate gland. 



X75- 



