THE UROGENITAL SYSTEM 



This system (Apparatus urosonitalis) includes two groups of organs, the uri- 

 nary and the genital. Tlu> urinary organs elaborate and remove the chief excretory 

 fluid, the urine. The genital organs serve 

 for the formation, development, and expul- 

 sion of the products of the reproductive 

 glands. In the higher vertebrates the two 

 apparatus are independent except at the 

 terminal part, which constitutes a urogeni- 

 tal tract, and includes the vulva in the 

 female and the greater part of the urethra 

 in the male. 



THE URINARY ORGANS 



The urinary organs (Organa uropoie- 

 tica) are the kidneys, ureters, bladder, and 

 urethra. The kidneys are the glands which 

 secrete the urine; they are red-brown in 

 color, and are situated against the dorsal 

 wall of the a])domen, being in most animals 

 almost symmetrically placed on either side 

 of the spine. The ureters are tubes which 

 convey the urine to the bladder. The latter 

 is an ovoid or pyriform sac, situated on the 

 pelvic floor when empty or nearly so; it is 

 a reservoir for the urine. The urine ac- 

 cumulates in the bladder until that organ 

 is full, and is then expelled through the 

 urethra. 



THE URINARY ORGANS OF THE 

 HORSE 



Fig. 374. — General Dorsal View of Urinart 

 Organs of Horse. 

 1, Right kidney; 1' , left kidney; Z, Z' . ad- 

 renal bodies; 3, 3' , ureters; 4, urinary bladder; 4'. 

 anterior end of bladder with cicatricial remnant of 

 urachu.s; 4", urethra; 5, aorta; 6, 6, renal arteries; 

 7, 7, external iliac arteries; 8, 8, internal iliac 

 arteries; 9, 9, umbilical arteries. (After Leisering'a 

 Atlas.) 



THE KIDNEYS 



Each kidney (Ren) presents two sur- 

 faces, two borders, and two extremities or 



poles, but they differ so much in form and position as to require a separate 

 description of each in these respects.' 



The right kidney (Ren dexter) in outline resembles the heart on a playing 

 card, or an equilateral triangle with the angles rounded off. It lies ventral to the 



' The kidneys are soft, pkistic organs, and hence an accurate knowledge of their form can 

 be gained only from a study of specimens wliich have been hardened in situ. The description 

 here given is based on this method. For this purpose subjects should be hardened in the standing 

 position to avoid artefacts. 



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