VIII Proceedings of the Association of American Anatomists 



PRELIMINARY REPORT OF EXPERIMENTAL WORK AND OBSERVA- 

 TIONS ON THE AREAS OF LANGERHANS IN CERTAIN MAMMALS. 

 By Lydia M. DeWitt. Department of Histology and Embryology, Uni- 

 versity of Michigan. 



I. By wax-plate reconstrnction of injected and nninjected areas of 

 Langerhans in man, rabbit, cat and rat, it is seen that these islands are 

 spherical or oval or irregular or lobnlated in form, vary .greatly in size, 

 both in animals of the same species and in animals of different species : 

 they consist of anastomosing irregular cords of cells forming a sponge- 

 like structure. One or several thin-Avalled blood vessels pass in tortuous 

 course through the central part of each area, divide several times, the 

 branches being connected by many anastomosing capillaries. I^umerous 

 capillaries and several larger vessels leave the areas and communicate 

 freely with the interacinar blood vessels. The large and irregular size 

 of the vessels, the thin walls and the similarity in structure of the afferent 

 and efferent vessels indicate that the circulation in the areas is sinusoidal. 



II. The operations on the twenty-eight cats used consisted in ligation 

 of the duct, division of the gland between two ligatures, cauterization of 

 the cut ends and sometimes tying a fold of omentum around the cut 

 ends of the gland. The animals were killed in from three to two hun- 

 dred days after the operation. Portions of the gland were removed for 

 microscopic study and the remainder extracted with water or glycerine 

 and its digestive action on proteids, starches and fats and also its 

 glycolytic action tested, the results in all cases being controlled by similar 

 tests with extracts of the normal portion of the same pancreas. The 

 microscopic changes consisted of atrophy of lobules and acini and increase 

 of connective tissue, the areas of Langerhans being in most cases well 

 preserved. In seven of the most successful experiments, the amylolytic, 

 steatolytic and proteolytic action was absent and in many others it was 

 much diminished, while the glycolytic action was not in any case 

 diminished. 



My results seem therefore to point to the conclusion that the areas of 

 Langerhans are vascular glands having a sinusoidal circulation in inti- 

 mate relation with the acinal blood supply; that they have a secretion 

 whose glycolytic action is equal to that of the normal pancreas and which 

 corresponds in its reactions and behavior to the activator principle of 

 the pancreas described by Cohnheim. 



ON THE ANATOMY OF A 4.0 MM. EMBRYO FROM THE HARVARD 

 EMBRYOLOGICAL COLLECTION. By J. L. Bremer. Emhryological 

 Laboratory, Harvard Medical Sclwol. 



