URINARY ORGANS OF THE OX 565 
The left kidney occupies a remarkable position, and when hardened in situ 
differs strongly in form from the right one. When the rumen is full, it pushes the 
kidney backward and across the median plane, so that it is situated on the right 
side, behind, and at a lower level than, the right kidney. It then les usually 
ventral to the third, fourth, and fifth lumbar vertebree. 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-lateral part the 
hilus, which opens laterally. The ventral surface is related to the intestine. The 
third face is 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 kidneys are embedded in a large amount of perirenal fat termed the 
eapsula adiposa. The weight of a kidney of an adult animal is about 20 to 25 ounces 
(ca. 600-700 gm.), the left one being usually an ounce or more the heavier. The 
two form about + per cent. of the body-weight. 
The right kidney measures about 8 or 9 inches (ca. 20-22.5 cm.) in length, 4 to 5 inches (ea. 
10-12 em.) in width, and 21% to 3 inches (ca. 5-6 cm.) in thickness. The left kidney is one or 
two inches (ca. 2 to 5 em.) 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 
Fic. 506.—Cast or OrtGIn oF UrEtER (a), Catyces Masores, AND CaLtyces Mrnores (b) of Ox. (After Dumont.) 
horse; in the right kidney it is an extensive elliptical cavity; in the left one it is a 
deep fissure. The pelvis is absent. The ureter begins at the junction of two wide, 
thin-walled tubes, the calyces majores; the anterior calyx is usually the larger. 
Each calyx major gives off a number of branches, and these divide into several 
funnel-shaped calyces minores, each of which embraces a renal papilla. The 
space not occupied by the calyces and vessels is filled with fat. 
On section through the kidney the renal pyramids are easily made out. The 
blunt apex of each pyramid, the renal papilla (Papilla renalis), projects into a calyx 
minor. On each papilla are small orifices (Foramina papillaria) by which the 
papillary ducts (Ductus papillares) open into the calyx. The renal columns are 
much more distinct than in the horse. 
At the hilus the renal artery is dorsal, the vein in the middle, and the ureter 
ventral; a quantity of fat surrounds these structures in the hilus. 
1The above statements refer to the adult subject, and are based on investigations made on 
living subjects, and studies of frozen sections and material hardened in situ. In the new-born 
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 rumen is pretty well filled. 
