Part 152

1, Cortical substance; 2, medullary substance; 3, renal crest; 4, renal pelvis; 5, ureter. (From Leisering’s Atlas, reduced.) ]

When the rumen is full, the left kidney (which is attached by a short mesentery) usually lies entirely to the right of the median plane, under the third, fourth, and fifth lumbar transverse processes. The primitive dorsal surface has become ventro-medial, and is somewhat flattened by contact with the rumen.

The =ureters= are, in general, like those of the horse, except in regard to the first part of the left one, which has a peculiar course, in conformity with the remarkable position of the kidney. It begins at the ventral part of the hilus (which faces toward the right), curves upward and inward over the outer aspect of the kidney to its dorsal surface, crosses the median plane, and runs backward on the left side.

The =bladder= is longer and narrower than that of the horse, and extends further forward on the abdominal floor. The peritoneal coat extends backward further than in the horse.

THE ADRENAL BODIES

The =right adrenal= lies against the inner part of the anterior pole of the right kidney. When hardened in situ it is pyramidal in form. Its inner surface is flattened and is in contact with the right crus of the diaphragm. The outer surface is convex and lies in the renal impression of the liver. The ventral surface is grooved for the posterior vena cava; on this surface a relatively large vein emerges near the apex. The base is concave and rests obliquely against the anterior pole of the kidney. The apex fits into the angle between the posterior vena cava and the dorsal border of the liver.

The =left adrenal= lies on the inner face of the posterior vena cava just behind the anterior mesenteric artery, and is therefore practically median in position. It is flattened, and irregularly triangular or heart-shaped in outline. Its left face is related to the dorsal sac of the rumen. Its right face is related to the vena cava, and presents a large emergent vein. The posterior border or base is deeply notched.

FIG. 386.—LEFT ADRENAL OF OX, VENTRAL VIEW: HARDENED in situ. ]

FIG. 387.—RIGHT ADRENAL OF OX, VENTRAL VIEW: HARDENED in situ. ]

It is interesting to note that the left adrenal does not migrate with the kidney, but retains its primitive position; it lies usually about two inches (ca. 5 cm.) in front of a transverse plane through the anterior pole of the left kidney.

The adrenals of the =sheep= are both bean-shaped. The right one lies along the anterior part of the inner border of the kidney, at the angle of the junction of the right renal vein and the posterior vena cava. It is a little over an inch (ca. 3 cm.) long, and about an inch (ca. 12 to 15 mm.) wide. The left adrenal is longer, flatter, and somewhat bent. It lies across the left renal vein, to which it is attached, but is not in contact with the kidney.

FIG. 388.—KIDNEYS OF PIG in situ, VENTRAL VIEW.

C.a., Hepatic artery; M.a., gastro-splenic artery. ]

FIG. 389.—FRONTAL SECTION OF KIDNEY OF PIG. ]

URINARY ORGANS OF THE PIG

The =kidneys= are smooth and bean-shaped; they are more flattened dorso-ventrally, more elongated, and smaller at the extremities than those of the dog. The length is about twice the width. They are usually almost symmetrically placed on either side of the first four lumbar vertebræ. (Variations in position are not rare, and involve the left kidney oftener than the right. The former has been found near the pelvic inlet.) The external border lies against the flank parallel with the edge of the longissimus muscle. The posterior extremity usually lies about midway between the last rib and the external angle of the ilium. The anterior extremity of the right kidney usually extends as far forward as the last rib, but has no contact with the liver.

The weight of the kidney of a medium-sized pig is about seven to nine ounces (200 to 250 grams). The ratio of their combined weight to that of the body is about 1 ∶ 150–200.

=Structure.=—The hilus is about in the middle of the inner border. The pelvis is funnel-shaped, and divides into two calyces majores, which pass in a curve forward and backward respectively, and give off some eight to twelve short calyces minores; each of the latter contains a papilla. Some papillæ are narrow and conical, and correspond to a single pyramid; others are wide and flattened, and result from the fusion of two or more pyramids; some project directly through the wall of the pelvis without the formation of a calyx. The renal pyramids are distinct, but it is apparent that some are compound, i. e., formed by fusion of primitively separate pyramids. The renal artery enters the ventral part of the hilus, and the ureter leaves it dorsally.

The only special feature in regard to the =ureter= is that it is at first relatively wide and gradually diminishes in caliber.

The =bladder= is relatively very large; when full, it lies chiefly in the abdominal cavity. It is almost completely covered with peritoneum.

URINARY ORGANS OF THE DOG

The =kidneys= are relatively large, forming about ¹⁄₁₅₀ to ¹⁄₂₀₀ of the body-weight; the weight of the kidney of a medium-sized dog is about two ounces (ca. 50 to 60 grams). They are both bean-shaped, thick dorso-ventrally, with a rounded ventral surface and a less convex dorsal surface; the surfaces are smooth.

The =right kidney= (Fig. 343) is not subject to much variation in position; it is situated usually under the last rib and the first three lumbar transverse processes. Its anterior part lies in the deep renal impression of the liver; its posterior part is related to the sublumbar muscles dorsally, and the pancreas and duodenum ventrally.

The =left kidney= (Fig. 342) is subject to some variation in position; this is due to the fact that it is loosely attached by the peritoneum, and is affected by the degree of fullness of the stomach. When the stomach is nearly empty, the kidney usually lies under the transverse processes of the second, third, and fourth lumbar vertebræ, so that its anterior pole is opposite to the hilus of the right kidney. As the stomach fills it pushes the left kidney backward, so that the anterior pole of the latter may be opposite the posterior pole of the right kidney. The dorsal surface is related to the sublumbar muscles. The ventral surface is in contact with the terminal part of the colon (Colon descendens). The external border is related to the spleen and the flank. The anterior extremity touches the stomach and the left extremity of the pancreas.

The external border of the left kidney has considerable contact with the flank, and hence it may be palpated more or less distinctly in the living animal about half-way between the last rib and the crest of the ilium.

=Structure.=—The hilus is in the middle of the inner border and is, relatively 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 papillæ, and thus tend strongly to produce a false impression. The pelvis is adapted to this arrangement of the medullary substance. It incloses a central cavity into which the renal crest projects, and is prolonged outward between 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= is abdominal in position, the neck lying at the anterior border of the pubic bones. It is relatively large, and when full, the vertex may reach to the umbilicus. It has a practically complete peritoneal coat.