84 



Mr. H. H. Dale. 



[Dec. 11, 



" The ' Islets of Langerhans ' of the Pancreas." By H. H. Dale, 

 B.Ch., George Henry Lewes Student. Communicated by 

 Professor Starling, M.D., F.K.S. Eeceived December 11, 

 1903 —Bead January 28, 1904. 



(From the Physiological Laboratory, University College.) 

 (Abstract.) 



These structures were first described by Langerlians in 1869. They 

 have since been found by many observers in the pancreas of every 

 species of mammal, bird, reptile, and amphibian in which they have 

 been looked for. Kuhne and Lea first recognised the peculiarly rich 

 plexus of wide blood-capillaries in the islets. As regards their function, 

 they have been regarded as connected with the nervous system, as 

 lymphatic structures, as embryonic remnants, as patches of exhausted 

 or degenerate pancreatic tissue, as furnishing a particular constituent 

 of the pancreatic juice, and as internally secreting ductless glandular 

 tissue, furnishing a substance necessary for normal carbohydrate 

 metabolism, and quite unconnected with the externally secreting 

 function of the pancreas. This last view has received support from 

 many observations of the degeneration or absence of the islets in 

 diabetes, and from the statement of several observers that, after 

 occlusion of the pancreatic duct, the islets remain intact when the 

 ordinary secretory tissue has disappeared. 



Lewaschew, in 1885, first stated that activity of the pancreas led to 

 an increase in the number of the islets, and that intermediate forms 

 between the ordinary secretory tissue and the islets could be found, 

 and were more abundant after activity. 



This statement has been confirmed by Pischinger, Maximo w, and 

 Tschassownikow, and has also been repeatedly contradicted. Laguesse 

 describes a perpetual change of secretory tissue into islets and vice versa, 

 the islets being, in his view, pancreatic tissue in an internally secreting 

 stage, and representing also the stage during which growth takes 

 place. 



My observations have been made on the pancreas of the dog, cat, 

 rabbit, and toad. The pancreas was hardened in a mixture of corrosive 

 sublimate and formaldehyde, sections cut in paraffin and stained with 

 toluidine-blue and eosine. The islets appear, with a low magnification^ 

 as relatively unstained areas. 



The pancreas was examined in conditions of " rest " (normal 

 activity), of exhaustion produced by prolonged administration of 

 secretin, and of starvation. Exhaustion was produced in the mammals 

 (cat and dog) by repeated injections of secretin into the jugular vein 

 during 6 — 12 hours, accompanied by bleeding towards the end of the 



