THORAX AND ABDOMEN OF THE HORSE 



1G5 



about 2 cm. This portion of the duct is known as the ainjndla, but it 

 is to be noted that the increase in diameter is caused by a thickening 

 of the wall by glandular tissue, and not by any increase in the lumen of 

 the tube. Beyond the ampulla the duct narrows abruptly. 



The seminal vesicles (Vesicula; seminales). — These are pear- 

 shaped, hollow bodies partly enclosed in the urogenital fold lateral to 

 the ampulhv of the deferent ducts and dorsal to the last part of the 

 ureters. Tlieir dorsal surface is in contact with the rectum. The main 

 part, or body (corpus), of each vesicle expands towards a rounded cranial 



Left ureter. - 

 Round ligament. 

 Left ductus deferens. 



Lateral umbilical fold. 

 Urinary bladder. 



Left seminal vesicle 



Left lobe of prostate. 



Isthmus of prostate. 

 Urethra. 



Left bulbourethral gland. 

 A. bulbi urethrse. 



M. bulbocavernosus 



Corpus cavernosus penis ( f^ 

 (in section). 



- Right ureter. 



Right ductus deferens. 



Urogenital fold. 



Right seminal vesicle. 



Cut edge of peritoneum. 



Prostatic utricle. 



M. prostaticus. 



M. urethralis. 



1/ /^ --^ — M. ischiocavernosus. 



Fig. 73. — Dorsal view of the urinary bladder and intrapelvic urethra of tlie male, 

 with their associated structures. 



extremity, the fundus, while its caudal end, approaching the middle 

 line, narrows to an excretory duct (ductus excretorius) that opens into 

 the urethra underneath the prostate. 



It is often stated that the excretory duct of the seminal vesicle joins 

 the termination of the deferent duct of its own side in a common 

 ejaculatory duct (ductus ejaculatorius); but in most horses the two 

 ducts open into the urethra by a common orifice (orificium ejaculatorium) 

 or diverticulum. 



The PROSTATio UTRICLE (Utriculus prostaticus). — When the dorsal 

 layer of the urogenital fold is removed, it is generally possible to find 



