478 



URINARY ORGANS OF THE OX 



and the inner one is in contact with the posterior vena cava. The anterior mesenteric artery 

 is nearly always more or less enlarged as a result of verminous arteritis, and the form and degree 

 of curvature of the left adrenal seem to vary in conformity with the condition of the artery. 



Structure. — The fibrous capsule adheres intimatelj^ to the surface of the organ. 

 It contains elastic fibers, and in its deep part unstriped muscle-fibers. From it 

 trabeculse puss radially into the substance, blending with the fine supporting reti- 

 culum. The parenchyma consists of a cortical and a medullary portion. The 

 cortical substance (Substantia corticalis) is red-brown in color, and is clearly 

 distinguishable from the yellow medullary substance (Substantia meduUaris). 



A large central vein (Vena centralis) is visible on cross- 

 sections. 



The cells of the cortex arc arranged in chains of one or two 

 rows. In the peripheral portion the cells are of high cylindrical 

 shape, and the chains form connecting loops; Giinther has pro- 

 posed the name zona arcuata for this part, instead of the usual 

 term zona glomerularis. More deeply the chains are distinctly 

 palisade-like, and this region is called the zona fasciculata. Next 

 to the medulla is the zona reticularis, in which the chains form 

 a network. The cells in these two zones are polygonal and con- 

 tain a brown pigment. 



Tlie cells of the medulla are arranged in irregular groups or 

 form sheaths around the veins. They react to chromic salts by 

 assuming a yellow or yellow-brown color, and are termed chromaf- 

 fin cells; they share this peculiarity with certain cells of the .sym- 

 pathetic ganglia and paraganglia, with which they are probably 

 related genetically. The alkaloid adrenalin appears to be formed 

 in the medullary cells. 



Vessels and Nerves. — The adrenals receive a rela- 

 tively large blood-supply through the adrenal arteries 

 (Aa. suprarenales), which arise from the renal arteries 

 or from the aorta directly. The veins terminate in the 

 posterior vena cava and the left renal vein. The lymph 

 vessels go to the renal lymph glands. The numerous 

 nerves are derived from the sympathetic system 

 through the solar and renal plexuses. The fibers 

 form a rich interlacement, especially in the medullary substance. Ganglion cells 

 are found chiefly in the medulla, but also occur in the deeper part of the cortex. 



Fig. 381. — Adrenal Body of 

 Horse; Horizontal Sec- 

 tion, Reduced. 

 1, Capsule; 2, 2', cortical 



subatance; 3, medullary substance; 



4, blood-vessel in section. (Froiu 



Leiseiing's Atlas, reduced.) 



URINARY ORGANS OF THE OX 



The kidneys are superficially divided into polygonal lobes by fissures of vari- 

 able depth. The lobes vary in size, and are commonly about twenty to twenty- 

 five in number. The fissures are filled with fat. 



The right kidney has an elongated elliptical outline, and is flattened dorso- 

 ventrally. It lies ventral to the last rib and the first two or three luml)ar transverse 

 processes. The dorsal surface is rounded, and is in contact chiefly with the sub- 

 lumbar muscles. The ventral surface is less convex, and is related to the liver, 

 pancreas, duodenum, and terminal part of the colon. The hilus is situated on the 

 anterior part of this surface near the inner ])order. The internal l)order is nearly 

 straight, and lies parallel with the posterior vena cava. The extcinal border is 

 convex. The anterior extremity occupies the renal impression of the liver, and is 

 capped by the adrenal body. 



The left kidney occuijies 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 



