ISLANDS OF LANGERHANS 



319 



that they form an internal secretion which enters the blood ves- 

 sels and exerts an influence upon carbohydrate metabolism. 



Ontogenetically the islands of Langerhans are derived from 

 the tubular acini but are separated therefrom during the third 

 month of fetal life (Pearce). * In the adult they appear to have 

 no connection whatever with the acini. In perfectly impregnated 

 specimens prepared by Dogiel f by the method of Golgi, no secre- 



FIG. 263. FROM THE HUMAN PANCREAS. 



a, acini; ft, is placed above an interlobular duct; c, an island of Langerhans ; a 

 second island, circular in outline, lies near the center of the figure. Hematein and eosin. 

 Photo, x 330. 



tory capillaries could be demonstrated connecting the cells of the 

 islands with the lumen of the acini. 



Blood Supply. The large blood vessels of the pancreas accom- 

 pany the interlobular ducts, but after repeated subdivision these 



* Amer. J. of Anat., 1903. 



f Arch. f. Anat., 1893. 



