The ultravioletray microscopic and histological observations upon Langerhans' islet of the rabbits which administrated sulfonyl-urea were performed, and results were as follows :
1) Ultravioletray absorption of the Langerhans' islet (2650Å and 2890Å) was considerably less compared with acinar cells of the pancreas.
2) Among the normal islet cells, two types of them were able to distinguish. There were, alpha cell which has distinct nucleolus, and nuclei and protoplasma with poor ultravioletray absorption and beta cell which has undistinct nucleolus, and shows strong and diffuse ultravioletray absoption.
3) After oral dose of sulfonyl-urea, once administration and continued administration, ultravioletrary absorption of beta cell's cytoplasma and nuclei were increased and got their maximum after 1 to 1 and a half hours.
4) Degranulatian of beta granules began a quarter hour after sulfonyl-urea administration and got their maximum after 3 hours, and after 6 hours, degranulation was yet remarkably observed through the Gomori's CHP staining.
5) Along these changings, hypertrophy of beta nucleus and 40% increase of averaged area was observed by karyometry.
6) The changings after sulfonyl-urea administration 0.5 g for 10 days were much resembled to that of once administration through Gomori's CHP staining.
7) Atrophy of the beta cells and strong glomeration of beta granules faced to the sinusoid of capillary vesells were observed in the rabbits' islets which administrated the drug once or continued.
8) No such remarkable changings were observed in the cases of sulfonyl-urea 0.1 g/kg int. v. administration for 1 month as oral dosed group.
9) Through-out these above mentioned data, it was conjectured that sulfonyl-urea has the influences upon beta cell to accelerate its function and secrete its insulin then decreases the blood sugar level.
