The own animal experimental investigations served the clearing of the most favourable variant of the operative technique in dog including organ perfusion and microsurgery. The middle-term endocrinic effects of a segmental transplant of nearly 35% of the pancreas from the dog were defined and the regulation of the endocrinic function of the denervated transplant was analysed. The morphological transformations in the transplant show new aspects by the exclusion of immunologic events. The evidence of the function of the transplant in vivo was led by the absolute lack of insulin after extirpating the transplant.

In 50 mongrel dogs autogenous heterotopic transplantation of pancreatic segments was performed without duct ligation. Analyses of the endocrine function of the transplant up to 275 days yielded reduced glucose tolerance and simultaneously normoglycaemia as well as stimulation of insulin release following administration of glucose and no early reflex insulin incretion following oral glucose administration. The exocrine pancreas tissue disappeared nearly completely and inside big complexes of isles mitoses could be observed. The A:B-cell relation had changed. The reduction of the transplanted tissue mass to one third was also evident by angiography.

The islets of Langerhans of metabolic healthy C57 BL KsJ mice have been characterized morphologically. By it they showed structures typical for Muridae as far as the A-cells formed a mostly single-layered shell around the compact complex of B-cells situated centrally. The electron-microscopical investigations rendered possible a well defined differentiation between A-, B-, and D-cells and also demonstrated no fundamental structural differences in comparison with the conditions existing in other rodents.

In Glandular intestinales der oberen Dünndarmes vom Hamster (Cricetulus griseus) lassen sich vereinzelt Zellen nachweisen, die histochemisch pseudoisocyanin positiv reagieren. Diese Zellen enthalten als Träger der Farbpigmentes zahlreiche Granula. Es wird vermutet, da*ß es sieh bei diesen Zellen um insulinbildende Zellen handelt.

Pseudoisocyanine-reacting cells could be identified in the intestinal glands of the upper duodenum of the hamster (Cricetulus griseus). These cells contain numerous granules as carrier substances of the colouring pigments. Presumable these cells are insulin-producing cells.

The islets of Langerhans of sand rats (Psammomys obesus) have been investigated ultrahistochemically in order to demonstrate biogenic amines. It could be found that amine-containing vesicles with a diameter of 600-700 nm from the type of catecholamine-granules exist in A-cells as well as in B-cells. It can be stated that the sand rat belongs to the species containing amines in A- and B-cells. The importance of the amines for the regulation of the hormone secretion of the islets of Langerhans is discussed and the connections to diabetes mellitus are referred too.

The tunica mucosa of the stomach and the other parts of the intestine (duodenum, jejunum, ileum and colon) of the dog has been investigated in order to demonstrate insulin producing cells. By means of the pseudoisocyanine-reaction it was possible to visualize in the lamina epithelialis of the stomach singular cells containing metachromatically reacting granules.

The statement that up to now no neural elements could be identified in the islets of Langerhans with the aid of electron microscopy led us to reinvestigate this question of innervation of the pancreas in spiny mice using light microscopy. Single nerve cells as well as nerve fibre bundles could be found in the interlobular connective tissue of the pancreas. By constrast, we could observe neither nerve cells nor nerve fibres in the islets of Langerhans. Extrainsular neuroinsular complexes could not be found either.

The tunica mucosa of the stomach and the other parts of the intestine (duodenum, jejunum, ileum colon) of the dog has been investigated in order t to demonstrate insulin producing cells. By means of thepseudoisocyanine-reaction it was possible to visualize in the lamina epithelialis of the stomach singular cells containing metachromatically reacting granules. It was possible to distinguish these cells from mast cells localised outside of the lamina epithelialis of the tunica mucosa. The value of this observation is given by the fact that until now hormone producing cells could be demonstrated in the laimina epithelialis of stomach and intestine of mammalia with exception of insulin-producing cells.

Reinecke-salt (ammonium tetracyanato diamine chromate) is known as amine precipitating reagens in applied chemistry. Its amine precipitates can be demonstrated in electron micrographes. The amine reineckates are unable to diffuse and difficult to dissolve. Depending from that they are localized in the cells. From our findings received in the boundary layer between adrenal cortex and adrenal medulla, we conclude that there are no non-specific precipitations with other cell components caused by Reinecke-salt. It could be determined that the catecholamines are accumulated in the cells of the adrenal medulla in granular shape in a typical manner. In the adrenal medulla cells of Acomys cahirinus first investigated by us we found amine containing vesicles with a diameter of 200 to 250 nm. In the neighbouring cells of the adrenal cortex no precipitates were visable. In the adrenal cortex we noticed the mitochondria from the tubulus typ specific for this region. The assumption that Reinecke-salt is a specific amine precipitating substance able of forming localized amin precipitates was confirmed by these investigations. So the Reineck-salt precipitation of biogenic amines is a new method beside the known ones for the ultrahistochemical amine demonstration. In our method the precipitation of amines by Reinecke-salt is the first step followed later by the tissue fixation with glutaraldehyde.

Histochemical and ultrahistochemical methods for the demonstration of biogenic amines are investigated with regard to their efficiencies and limitations. For the purposes of the light microscopy fluorescent histochemical methods at present are sufficient. Hereby beta-arylethyl-amines and indolalkylamines are demonstrable with formaldehyde or glyoxylic acid whilst histamine is traceable with o-phthaldialdehyde. In this connection those chemical and physical conditions of this methods are shown, under which the demarcation and quantitative determination of the several amines is possible. Ultrahistochemically biogenic amines can be demonstrated by means of the chromaffine and the argentaffine reaction, the reaction with permanganate and the REINECKE-salt precipitation technique. Apart from the latter one, all these methods are based on an initially reaction between glutaraldehyde and amines. Thus these techniques might be founded on one and the same principle. Besides, the demonstration of adreanline as a secondary amine might be hindered also by the fact that the product of its reaction with glutaraldehyde is soluble in water. On the other hand the reaction product of primary amines with glutaraldehyde is insoluble in water. When using REINECKE-salt the correctly localizated precipitation of amines is the first step of the reaction. After that the treatment with glutaraldehyde is only serving for the fixation of the tissues. But the ultrahistochemical methods mentioned above altogether are showing a deficiency as far as they do not allow to make the several amines selectively visible. Therefore a quantitative ultrahistochemistry of biogenic amines is still impossible at present.