748 



THE URINAEY TRACT. 



silver; and C. Ludwig,* also by the silver stain, first indicated their presence 

 in the urinary tubules. 



Such an endothelial layer, present in all varieties of the urinary tubules, 

 is best visible in the front view of the structureless membrane, where the 

 -epithelium is stripped off. Here the endothelia are comparatively large, irreg- 

 ularly polyhedral bodies, with distinct central nuclei. The nucleus has a 



plainly marked shell, containing in 

 its interior a few small nucleoli, the 

 nuclei being mostly of oblong shape. 

 In the body of the endothelium a 

 2) delicate reticulum is seen with very 

 minute nodulations. Each body is 

 separated from all its neighbors by 

 a delicate light rim of cement-sub- 

 stance, which is traversed at right 

 angles by extremely minute fila- 

 ments or thorns. In side view, ob- 

 viously, these bodies will exhibit a 

 spindle-shape, the broadest portion 

 of the spindle corresponding to the 

 central nucleus. 



If the views of recent observers 

 are correct namely, that the struct- 

 ureless layer, synonymous with the 

 hyaline or basement-layer, is an ag- 

 gregation of endothelia infiltrated 

 with elastic substance this view 

 may also be applied to the struct- 

 ureless membrane of the urinary 

 tubules. In normal kidneys I failed 

 to discover nuclei in the structure- 

 less layer proper, which would indi- 



FIG. 337. CONVOLUTED TUBULE 

 FROM A HUMAN KIDNEY AFFECTED 

 WITH ACUTE CATARRHAL (INTER- 

 STITIAL) NEPHRITIS. OBLIQUE SEC- 

 TION. 



P, Inflammatory corpuscle, sprung from the 

 division of an epithelium ; D, cluster of inflam- 

 matory corpuscles, sprung in the same man- 

 ner ; R, rods of cuboidal epithelia, still recog- 

 nizable ; E, endothelia, increased in size and 

 number. Magnified 1200 diameters. 



cate their construction of former 

 endothelia, In inflamed kidneys, 

 on the contrary, no doubt was left 

 as to the fact that the structureless 

 layer is composed by a number of 

 closely attached, in part nucleated, 

 endothelia. 



In the inflamed kidney the endothelial layer beneath the epithelial is 

 always more marked than in the normal kidney. In chronic catarrhal (in- 

 terstitial or desquamative) nephritis, all the tubules that have lost their 

 epithelial investment invariably show an investment of endothelia. 



This, in the transverse section of the tubule, is characterized by the pres- 

 ence of flat, irregularly spindle-shaped bodies, which are always more coarsely 

 granular than in the physiological condition. Their nuclei are also more 

 coarsely granular, sometimes homogeneous. The flat shape, the large size in 

 the frontal diameter, and the construction of the nuclei serve for an accurate 

 contradistinction to epithelia. I have failed in obtaining specimens indicative 



Hand-book of Histology," by S. Strieker, London, 1874. 



