11)2 JOHX SUNDWALL 



described. In fresh safraiiin-acid violet the nuclei stain red 

 while the granules stain a dark greenish blue. The advantage 

 of this stain lies in this contrast. In the large bulging cells 

 the red flattened basal nuclei are generally seen while in the 

 other stained cells they are made out with difficuhy since the 

 colors of nuclei and granules are similar. 



The granules in the cells of the intercalary duct stain similarly 

 to those of the tubules. Lumina are always seen but vary in 

 diameter. The cells are generally uniform in size and shape. 

 No bulging cells are seen. In each cell there is a narrow zone of 

 non-granular cytoplasm surrounding the granules. No ^^ari- 

 ations are seen in the size, shape, and position of the nuclei 

 whether the cell contains the maximum of granules, only a 

 narrow zone at the proximal end, or no granules whatsoever. 

 They are similar in structure and staining characteristics to 

 the round and oval nuclei seen in the tubules. 



In thin sections stained with neutral gentian the outer layer 

 of cells surrounding the secretory cells of the intercalary duct 

 are readily made out. Near the oiigin of the duct these cells 

 ai-e still more or less cuboidal but towards the tubular end the 

 cells with their nuclei become more and more elongated. These 

 cells stain more faintly than do those of the inner layer. They 

 surround the tubule as elongated cells between the secreting 

 elements and the basal membrane (see Connective Tissue.) 



As in the case of the iron haematoxylin stained sections one 

 is especially struck by the various intensities which these granules 

 stain with neutral gentian and safranin-acid violet. In well 

 fixed tissues the majority of granules stain deeply in both of 

 these dyes. However, one frequently sees in the same cell, in 

 both the tubules and the intercalary ducts, granules lying in 

 close proximity to each other some of which are stained deeply 

 blue, others only faintly yellow or brown, and still others barely 

 stained at all. This variation in intensity of staining is in no 

 way related to the position of the granule or its size. Cells 

 are frequently seen bordering each other, one possessing deeply 

 stained blue granules throughout, the other possessing yellow- 

 ish brown or fnintlv stained gi'amiles. Tli(> jirobable exi)ln- 



