Abstract
Since the first histochemical demonstration of zinc in the islet of Langerhans by Okamoto (1942), it has been generally believed that zinc plays an important role in the secretory function of the islet. However, details have not been sufficiently analyzed, partly because of methodological difficulties.
In this paper, an improved histochemical method for zinc was developed which was sensitive enough in paraffin section.
Procedures as follows :
1) Fix a small piece of pancreas for 3-5 hrs in ice-cold 70%, ethanol saturated with H2S. 2) Dehydrate in ascending alcohol, xylol and embed in paraffin. 3) Cut at 6μ (rabbit) or 15μ (rat). 4) Mount on slides with albumin-glycerin and dry for 24hrs at 45°C. 5) Deparaffinize in xylol, alcohol and cover with 0.1% celloidin. 6) Treat for 2-6 hrs at 56°C in the dithizone-ammonia sloution (mix 400mg of dithizone in 1 ml of 28% ammonia water, dilute to 10ml by adding aq. dest., keep for 10min at 70°C in water bath, filter, and add 2ml of the filtrate to 100ml of aq. dest.). 7) Wash gently in 56°C water. 8) Mount in Kaiser's glycerogel.
With this method, the islet cell zinc was demonstrated as fine purple granules without diffusion. And identification was performed by the absorption spectrum analysis of the extract from the stained islet tissues. Mechanism and advantages of the method were discussed.
