URINARY ORGANS OF THE OX 



479 



side, behind and at a lower level than the right kidney. It then lies usually under 

 the third, fourth, and fifth lumbar vertebrae. When the rumen is not full, the left 

 kidney may lie partly to the left of the median plane. It has three surfaces. The 

 dorsal surface is convex, and presents on its antero-external part the hilus, which 

 opens outward. The ventral surface is related to the intestine. The third face 



External border 



AnUriar extrcmilij 



Ureter Renal artery 



Fig. 382. — Right Kidney of Ox, Ventral Face. 

 Organ hardened in situ. Fat has been removed from fissures between lobes. 



is often more or less flattened by contact with the rumen, and may be termed the 

 ruminal surface. The anterior extremity is small, the posterior large and rounded. 



The preceding statements refer to the adult subject, and are based on investigations made on 

 hving subjects, and studies of frozen sections and material hardened in situ. In the young 

 calf the kidneys are almost symmetrically placed, but as the rumen grows it pushes the left kidney 

 to the right and backward pari passu. It also usually causes a rotation of the kidney, so that the 

 primary dorsal surface comes to lie almost in a sagittal plane. Further, the gland is bent so that 

 the hilus is largely closed up and faces outward (to the right). In very fat subjects the three- 

 sided appearance of the kidney may be absent, and about one-third or more may remain to the left 

 of the median plane, even where the rinnen is pretty well filled. 



The kidneys are embedded in a large amount of perirenal fat. The weight 



Renal artery 



Fig. 383. — Frontal Section of Kidney of Ox. 

 L, Lobes of cortex; P, papillae; C, calyx major; c', calyces minore."?. 



of a kidney is about 20 to 25 ounces (ca. 570 to 700 gm.), the left one being usually 

 an oimce or more the heavier. The two form about }4 per cent, of the body-weight. 



The right kidney measures about 8 to 10 inches (ca. 20 to 25 cm.) in length, 4 to 5 inches (ca. 

 10 to 12 cm.) in width, and 23/2 to 3 inches (ca. 7 cm.) in thickness. The left kidney is one or 

 two inches (ca. 2 to .5 cm.) shorter, but its posterior part is much thicker than the right one. 



Structure. — The hilus is equivalent to the hilus and sinus of the kidney of the 

 horse; in the right kidney it is an extensive elliptical cavity, in the left, a deep 

 fissure. The pelvis is absent. The ureter begins at the junction of two wide, 



