VESICUIwE SKMIXALES. 



535 



and the convex side towards the rectum. It is retained firmly in its posi- 

 tion by the two superior and two inferior tendons of the bladder, by the 

 attachments of the pelvic fascia, and by a process of the internal layer of 

 the deep perineal fascia, which forms a sheath around the membranous 

 urethra, and is inserted into the apex of the gland. It consists of three 

 lobes, two lateral and a middle lobe or isthmus ; the lateral lobes are 

 distinguished by an indentation upon the base of the gland, and by a slight 

 furrow upon its upper and lower surface. The third lobe or isthmus is a 

 small transverse band which passes between the two lateral lobes at the 

 base of the organ. In structure the prostate gland is composed of ramified 

 ducts, terminating in lobules of follicular pouches, which are so closely 

 compressed as to give to a thin section of the gland a cellular appearance. 

 It is pale in colour and hard in texture, splits easily in the course of its 

 ducts, and is surrounded by a plexus of veins which are enclosed by the 

 strong fibrous membrane with which it is invested. Its secretion is poured 

 into the prostatic portion of the urethra by fifteen or twenty excretory 

 ducts. The urethra in passing through the prostate lies one-third nearer 

 its upper than its lower surface. 



VESICULJE SEMINALES. 



On the under surface of the base of the bladder, and converging towards 

 the base of the prostate gland, are two lobulated and somewhat pyriform 

 bodies, about two inches in length, the vesiculaB seminales. Their upper 

 surface is in contact with the base of the bladder ; the under side rests on 

 the rectum, separated only by the recto-vesical 

 fascia ; the larger extremities are directed back- 

 wards and outwards, and the smaller ends almost 

 meet at the base of the prostate. They enclose 

 between them a triangular space, which is 

 bounded posteriorly by the recto-vesical fold of 

 peritoneum, and which corresponds with the 

 trigonum vesicae on the interior of the bladder. 

 Each vesicula is formed by the convolutions of 

 a single tube, which gives off several irregular 

 caecal branches. It is enclosed in a dense 

 fibrous membrane, derived from the pelvic 

 fascia, and is constricted beneath the isthmus 

 of the prostate gland into a small excretory 

 duct. The vas deferens, somewhat enlarged 

 and convoluted, lies along the inner border of 

 each vesicula, and is included in its fibrous in- 

 vestment. It communicates with the duct of the vesicula, beneath the 

 isthmus of the prostate, and formsf the ejaculatory duct. The ejacula- 



* The posterior aspect of the male bladder ; the serous covering is removed in order 

 to show the muscular coat. 1. The body of the bladder. 2. Its fundus. 3. Its inferior 

 fundus or base. 4. The urachus. 5, 5. The ureters. G, 6. The vasa deferentia. 7, 7 

 The vesiculse seminales. The triangular area, bounded by the vasa deferentia and 

 vesiculae seminales on either side, a dotted line above and the numeral 3 below, is the 

 space corresponding with the trigonum vesicae. It is this part of the bladder which is 

 pierced, in puncturitg the bladder through the rectum. The dotted line, forming the 

 base of this triangulai area, marks the extent of the recto-vesical fold of the peritoneum 



f It has been customary hitherto, in works on anatomy, to describe the course of ex- 

 cretory ducts as proceeding from the gland, and passing thence to the point at whu-h 



Fig. 235 * 



