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OF THE URINARY ORGANS. 



§ 185. 



The urinary organs consist of the two kidneys — true 

 glands, having a tubular structure, which secrete the urine — 

 and of the secretory urinary passages, the ureters, bladder, and 

 urethra. 



§ 186. 



In the kidneys, are to be distinguished the coats and the 

 secreting parenchyma. To the former belong the adipose 

 capsule, as it is termed (capsula s. tunica adiposa), constituted 

 of lax connective tissue abounding in fat cells, scarcely 

 deserving the name of a special membrane, and the fibrous 

 tunic (tunica propria s. albuginea), a thin but strong coat, of 

 a whitish colour, composed of common connective tissue and 

 numerous fine elastic networks, which closely invests the kidney, 

 and, at the hilus, is in apposition with the pelvis of the gland 

 and the vessels, but does not penetrate into the interior of the 

 organ. 



The secreting parenchyma, which is abruptly denned from 

 the fibrous membrane, consists, as seen by the naked eye, of 

 two portions, the medullary and the cortical substance, the 

 former of which constitutes 8 — 15, isolated, conical, masses 

 converging towards the hilus, the pyramids of Malpighi ; whilst 

 the latter forms the entire cortical part of the organ, and 

 moreover, sends processes between the separate pyramids 

 which extend as far as the hilus, — the columns Bertini, — and is 

 apparently continuous throughout the gland. Examined mi- 

 croscopically, however, the cortical substance is found to be 

 divided into as many segments as there are pyramids and the 

 kidneys, therefore, may be regarded as made up of a certain 

 number of large, though closely connected lobes. 



§187. 

 Composition of the renal substance. — Both portions of the 

 kidneys consist, essentially, of the uriniferous canals (tubuli 

 it. 13 



