CYTOLOGICAL STUDIES OF LANGERHANS S ISLETS 7 



Trophospongia are also found in islet cells. Holmgren ('04) 

 was the first to describe this network as being connected with 

 the processes of interstitial cells and which can often be canal- 

 ized. Tschassownikow ('06) stated that the trophospongium of 

 the islet cell was not constant, while Bensley ('11-12) claimed 

 to have observed it in both fresh and fixed preparations. 



The occm-rence of mitochondria in the islet cells was described 

 by Bensley ('11-'12), Herwerden ('12), and Arnold ('12). Ac- 

 cording to these authors, the mitochondrial substance is present 

 in the form of either minute granules or delicate filaments, the 

 thick, coarse chondrioconts, such as are seen in the acinus cell, 

 being entirely lacking. 



It will be seen from these observations that the protoplasm of 

 the islet cell presents either a homogeneous or a reticular appear- 

 ance, and that the islet cells are of two kinds, distinguishable 

 from each other by the tingibility of the plasma and by differ- 

 ence in granular content. It was also reported that fat droplets, 

 mitochondria, and the intracellular network may occur in the 

 islet cell, to which, however, no special importance has yet been 

 ascribed. 



Concerning the nuclei of these cells, the observations of vari- 

 .ous investigators are not in accord. The nuclei are described as 

 being either smaller or larger than those of acinus cells, and the 

 occasional occurrence of even giant-nuclei has been pointed out. 

 They may be spherical, elliptical, or even rod-shaped. Many 

 investigators believe that the nucleus has a dense reticulum which 

 is rich in chromatin corpuscles, while others say that it is poor 

 in these granules. Such diversity of opinion may be due to the 

 technical methods employed. The only point of coincidence is 

 that the nucleoli are either very small or altogether absent from 

 the nucleus. 



Observations 



Specific granules: Cell types: the nucleus. We designate as 

 specific granules of the islet cell those minute granules which are 

 seen in the preparations fixed in sublimate-osmic-chromic acid, 

 formalin, Maximow's, Regaud's, Meves's or Zenker's fluid, and 



