144 EQUINE ANATOMY. 



SUPRA-RENAL CAPSULES. 



The supra-renal capsules are two small elongated bodies lying 

 to the under and inner side of the pelvis of the kidney. 



Form. — Elongated and flattened, two inches long; right larger. 



Structure. 



External fibrous coat, which projects inward, forming spaces. 



Parenchyma. 



(a) Co rti cat substance. Dark-brown in color, and consists of 

 granular nucleated cells. 



(b) Medullaij substance. Yellow and soft, of a delicate reti- 

 cular structure filled with cells and nerve structures. 



Vessels. — Mesenteries and renal. 



Nerves. — In large numbers from solar plexus. 



THE URETERS. 



The ureters are two in number, beginning at the pelvis of the 

 kidney, run back and downward to the superior and posterior 

 portion of the bladder, where they penetrate its muscular coat for 

 an inch before opening into its interior. It is the size of a goose 

 quill. 



Structure. 



Exterfial, fibrous layer ; middle , of external, circular and inter- 

 nal longitudinal muscular fibre, and an interna/, mucous, ridged in 

 its long axis, and covered with stratified pavement epithelium. 



THE BLADDER. 



This is a muscular bag in which the urine is accumulated before 

 being discharged from the body. It occupies the inferior part 

 of the pelvic cavity, and has three openings, the orifices of the 

 two ureters and beginning of the urethra. 



Weight, sixteen ounces. 



Parts. 



Near the urethral opening, the neck; between the urethral 

 opening and the openings of the two ureters a triangular space, 

 the trigone. It rests by its inferior surface, or base, on the pubo- 

 ischial symphysis. Its anterior extremity orfujidus is in relation 

 to the large colon. Above, it is in relation with the uterus and 

 vagina in the female, the seminal vesicles and rectum in the 

 7nale, 



