THE URINIFEROUS TUBULES 



345 



i 



isolated, or if outlined by impregnation with silver salts, the bor- 

 ders of the epithelial cells are extremely irregular and are deeply 

 fluted or serrated, the serrations of each cell interdigitating with 

 those of its neighbors. The 

 deep fluted serrations of the 

 interlocked epithelium gives 

 many of its cells a coarsely 

 striated appearance, the stri- 

 ation being more prominent 

 beneath the centrally situated 

 nucleus than in the apical 

 portion of the cell. Other 

 longitudinal striations in the 

 proximal or basal portion of 

 the cell are the result of a 

 linear arrangement of the 

 coarse granules which occur 

 in this part (R. Heidenhain *). 

 These appearances often give 

 the epithelium of the convo- 

 luted tubules a peculiar stri- 

 ated or "rodded" character. 



The apices of the epithe- 

 lial cells are very easily de- 

 stroyed, but when perfectly 

 preserved often present a 

 delicately striated, cuticular 

 border. The remaining portions of the cytoplasm are finely 

 granular. 



The nuclei of the epithelial cells of the convoluted tubules are 

 spherical in shape, and do not stain very deeply with nuclear dyes 

 as compared with the more distinct and deeply staining nuclei of 

 the collecting tubules. Thus they appear as if partially clouded 

 by the granular cytoplasm, an appearance which is greatly exag- 

 gerated with the onset of acute inflammatory processes, which, 

 on attacking the kidney, are prone to involve the convoluted 

 tubules. The chromatin is quite evenly distributed throughout 

 the nucleus and the nuclear membrane is not easily demonstrated. 



The lumen of the convoluted portion of the uriniferous tubule 

 is of variable caliber ; it presents frequent slight dilatations. 

 * Arch. f. mik. Anat., 1874. 



FIG. 284. FROM A LONGITUDINAL SECTION OF A 

 CONVOLUTED TUBULE OF THE GUINEA PIG'S 



KIDNEY. 



The cell outlines have been blackened by 

 the Golgi method. Very highly magnified. 

 (After Landauer.) 



