THE KIDXEYS 



1011 



the periphery; others forming a part of the colunins of Berlin, and flisposed almost 

 at ri<rht an<:l('s to the last. These cortical groups arc called pyramids of Ferrein, 

 in contradistinction to the mnch larger nicdullarv pyramids of ,Mali)ii:lii. 



The kidney of a foetns differs from that of the adult in the lo])ular suljdivision of 

 its surface, each lobule corresponding to the l)ase of a pyramid of Malpighi ca[>ped 

 by a thin layer of cortex. Such a condition is permanent in some of the lower 

 animals; but in man the superficial indications of morphological segmentation 

 usually become obliterated during the progress of growth of the cortical tissue, and 

 are s<'l(loin visiltle after the age of ten. 



Urinifercus tubes (tig. (U4). — The secreting tubules commence ])y a number 

 of spherical capsules (capsules of Bowman), Avbich lie'in the cortex. From each 

 capsule ])nsses a tul)e witli a narrow iieek, which l)ecomes wide and convoluted, 

 then, nai-i-o\ving again, runs down into the suljjacent ]\Iali)ighian pyramid, forms 

 a loop (looped tube of Henle), returns into the cortex, where it again becomes 

 dilated and contorted, and, after undergoing a final constriction, opens into a 

 straight collecting tube, the axial element of a pyramid of Ferrein. The collect- 

 ing tubes run into the Malpighian pyramids, and unite with each other to form a 



Fig. (JIj. — JIuHizuxTAL .Section of Kidney, showing the Sincs. 



CORTEX WITH PYRAMIDS 

 OF FERREIN 



Branch OUCT Portion Irregular 



0/ of fatty branch 



artery capsule of artery 



smaller number of larger tubes, which terminate l)v opening on to the papillary 

 ajjcx of the pyramid, and into the corresi)onding calyx of the duct. The tul>es arc 

 lined with epithelium throughout, the cells being tesselated in the capsule, irregu- 

 larly cubical in the convoluted tubes, flattened on the loops of Henle, and columnar 

 in the cortical collecting tubes and in the straight tubes of the medulla. 



Vessels (fig. (514). — The kidney is very vascular. The larger arterial liranehes. 

 if traced in section from the point at which they ])ierce the bottom of the sinus, will 

 l)e found to run u]i between tlie jtyramids of Mal)»ighi to subdivide at their bases 

 into cortico-medullary arches wbieli lie between the cortex and medulla, giving 

 off arterioles in both directions, the cortical branches sup] living afferent twigs to 

 the glomeruli within the capsules of Bowman; the medullary branches running 

 inwards to form ph-xuses around the straight and looj)ed tut»ules of the Malpighian 

 pyramids. The efferent vessels of the Malpighian glomeruli form a capillary 

 l)iexus around the uriniferous tubules and tt'rminate in the renal veins. The sur- 

 face of the kidney receives small collateral arteries whicli pass through the fatty 

 capsule from the su]irarenal. spermatic, and lumliar v(\ssels. The su])erficial veins 

 appear in the form of little stellate groups (stars of Verheyen », which eonnnuni- 



