CYTOLOGICAL STUDIES OF LANGERHANS's ISLETS 15 



the cells or in the nuclei. This and the fact that the islet is 

 composed mainly of cells of this type, rather strongly suggest 

 that the lipoid corpuscles are a cell constituent which plays an 

 important part in the function of the islet. It is presumable 

 that this lipoid substance is to be extruded, either as such or 

 after having undergone certain changes, into the blood-vessel 

 with which the cells in question are intimately connected. 



The urano-argentophile apparatus. By the term urano-argent- 

 ophile apparatus, I understand those filamentous or granular 

 corpuscles which can be made manifest by the Cajaluranic nitrate- 

 silver method. Since this method is one which is employed for 

 exhibiting the Golgi intracellular network apparatus, the question 

 arises whether the urano-argentophile and the Golgi apparatus 

 are to be identified or not. In fact, I have found that the same 

 intracellular network can be brought into view in pancreatic 

 acinus cells not only by the Kopsch, Sjovall, and Weigi method, 

 but also by the Cajal method. This is not, however, the case 

 with islet cells; the Cajal method does not exhibit the net, but a 

 different apparatus which can easily be distinguished from it 

 by both its morphological and chemical characteristics, and which 

 therefore must be treated of separately. 



The urano-argentophile apparatus is stained brown or black 

 with the Cajal method, as mentioned above, so that it stands 

 out clearly from the faintly staining ground substance of the 

 protoplasm (figs. 6, 28 to 31). These corpuscles are filamentous 

 or granular in shape. The filaments are of varying thickness 

 and length and are more or less tortuous in their course. They 

 rarely ramify or anastomose with one another, and are usually 

 distributed evenly throughout the cytoplasm, although it often 

 occurs that they are gathered together in a given region of the 

 cell-body. The thinner filaments have an even contour, while 

 the thicker ones often have spherical or fusiform enlargements 

 along their course, which may be set free and may give rise to 

 urano-argentophile granules. The latter, spherical or oval in 

 shape, are also of various sizes, and stain more heavily than the 

 filaments. They are either evenly scattered throughout the cy- 

 toplasm or accumulated at one or both ends of the cell. Neither 



THE AMERICAN JOURXAL OF ANATOMY, VOL. 28, NO. 1 



