570 URINARY ORGANS OF THE DOG 
wide. Cortex, limiting zone, and medulla are clearly defined. On frontal sections 
it is seen that the medullary substance forms a horizontal renal crest like that of 
the horse, but with the important difference that curved ridges proceed dorsally 
and ventrally from the crest somewhat like buttresses. Sections above or below 
the renal crest often cut these ridges in such a manner as to give the appearance 
of conical papille, and thus tend strongly to produce a false impression. The 
pelvis is adapted to this arrangement of the medullary substance. It encloses a 
central cavity into which the renal crest projects, and is prolonged outward be- 
tween the ridges, forming cavities for the latter, thus simulating the appearance 
of calyces which do not exist. 
The ureters present no special features. 
The bladder, when full, is abdominal in position, the neck lying at the anterior 
border of the pubic bones. It is relatively large, and when distended, the vertex 
may reach to the umbilicus. When empty and contracted, it is usually entirely in 
the pelvic cavity. It has a practically complete peritoneal coat. 
THE ADRENALS 
The right adrenal lies between the anterior part of the medial border of the kid- 
ney and the posterior vena cava. It is somewhat prismatic, and is pointed at 
either end. The left adrenal lies along the posterior aorta, from the renal vein 
forward, but is not in contact with the kidney. It is elongated and flattened dorso- 
ventrally. (There is a furrow on the ventral surface for the phrenico-abdominal 
vein which crosses it; the part in front of this furrow is discoid, and may be taken 
for the entire organ in a fat subject.) The cortex is pale yellow in color, the me- 
dulla dark brown. 
