The ultrastructure of the nervous elements in Langerhans islets of Psammomys obesus has been studied. A great variety of neural structures present in the islets has been described: neuroganglion-, enterochromaffin- and satellite Schwann cells (neuro-insular complexes type I) and cholinergic, adrenergic and peptidergic nerve fibers (neuro-insular complexes type II) in direct contact with the endocrine cells. In the pericapillary space typical neuro-vasal endings of neurosecretory type have been described. The islets of Langerhans and some of the endocrine cells have a total or partial glial sheath. These findings support the thesis of the paraneuronal nature of the endocrine cells of the Langerhans islets.

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PubMedDate not supplied

Effects of cyclosporin A on the endocrine pancreas of the rat. Morphological and immunohistochemical studies.

Treatment with the immunosuppressive agent cyclosporin A frequently gives rise to functional alteration of the islets of Langerhans which may result in diabetes. Light microscopy, immunocytochemical, and electron microscopy investigations demonstrate degranulation, vacuolization, and destruction of endocrine pancreatic cells in treated animals. Similar changes, but of a milder degree, are observed in the A-cells. The morphological alterations described are likely to be the result of inhibition of synthesis and secretion in B-cells.

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PubMedDate not supplied

Morphological changes in pancreatic B-cells after intravenous administration of forskolin.

The morphological changes in rat pancreatic islets were studied after intravenous injection of forskolin (1.5 mg/kg), an activator of adenylate cyclase, to male Wistar rats. A high amount of insulin containing granules was observed on PAP immunostained paraffin sections. Ultrastructural study of islet B-cells demonstrated enlarged perinuclear space, dilated cisternae of rough endoplasmic reticulum and activated Golgi complex with numerous vesicles. The results suggest that intravenous administration of forskolin produces a modest increase of B-cell synthetic activity in the pancreatic islets of rats. It is assumed that forskolin affects pancreatic B-cells via increased cAMP.

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PubMedDate not supplied

The problem of -granule ultrastructure in the endocrine pancreas.

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