4G2 



URO-GENITAL SYSTEM. 



Fig. 126. Diagram of the kid- 

 ney and its circulation.* 



the same or near the point where the afferent vessel enters 

 (Fig. 1 26, p V). But it must be noted that the efferent vessel 

 does not immediately reunite with 

 its fellows to form the renal vein ; 

 almost immediately after it has left 

 the glomerulus it divides again and 

 forms a capillary system in the renal 

 parenchyma (RC), the vascular net- 

 work of which interlaces with the 

 uriniferous tubes. This efferent ves- 

 sel does not merit the name of a 

 vein ; it belongs to a separate sys- 

 tem which we might perhaps con- 

 sider as a renal portal vein, since it 

 is intermediate between two capil- 

 lary systems, viz., the glomeruli and 

 the renal parenchyma ; the true ori- 

 gin of the renal vein is subsequent 

 to these last-named capillaries. 



This arrangement of the vascular 

 system in the kidney forms the basis 

 of all the modern theories upon the urinary secretion; & filtra- 

 tion is the fundamental process on which these theories depend. 

 If we recall the fact that differences of pressure between 

 the various parts of the circulatory system do not bear any 

 relation to the especial form of these parts (trunks, small 

 vessels, or capillaries), but to their distance from two extreme 

 points (left ventricle and right auricle) of the origin andter- 



of the pyramids of Ferrein (alongside of the tubules of Bellini), 

 then reascend again, becoming larger, and go into the cortical sub- 

 stance; there these tubes take a new direction, and finally continue 

 with the true tubes of Bellini. In brief, the tubes of Henle become 

 loops in form of inverted siphons between the tube of Ferrein and 

 that of Bellini. The only physiological knowledge that we at 

 present possess of these looped tubes is dependent on their constric- 

 tion in the descending branches, and the dilatation in their ascend- 

 ing branches. Yet their epithelium is clear and transparent in the 

 straight and descending branch, turbid and granular in the large 

 and descending portion (towards the bases of the pyramids). (See 

 Ch. Fr. Gross, " Essai sur la Structure Microscopique du Rein." 

 These de Strasbourg, 1868, No. 95.) 



* T6, Straight tube of Bellini. T/*, Convoluted tube of Ferrein. G, Glom- 

 erulus, with its vascular tuft, a, Afferent arteriole, going to the capillaries of 

 the corpuscle. pV, Efferent vessel forming smaller capillaries among the renal 

 tubuli in KG, before forming the true venous vessel V. 



