Light and electron microscopy of the pancreas of the Egyptian one-humped camel(Camelus dromedarius)

ABSTRACT

The exocrine portion of the pancreas consists of the pancreatic acini and their ducts. Hormones are synthesized by the cells of islets of Langerhans; they include insulin- (β- cells), glucagon- (α-cells), somatostatin- (∆-cells), and pancreatic polypeptide- (F- or PP-cells) immunoreactive cells. This study discusses the light and electron microscopic architecture of both the exocrine and endocrine pancreas of the dromedary camel. The cells of the pancreatic acini were pyramidal in shape with large spherical and centrally located heterochromatic nuclei. The basophilic basal and eosinophilic apical regions seen under the light microscope showed concentrated rough endoplasmic reticulum and homogenous electron-dense zymogen granules, respectively, on ultramicroscopy. Abundant elongated numerous mitochondria and Golgi complexes were found in the cytoplasm. The islets were scattered randomly among the acini and appeared as irregular spherical or oval masses of cells in light microscopy. The islet cells could be identified based on their location, cytological features, density of granules, and the degree to which the granule matrix was separated from its limiting membrane by an electron-dense area. The peripherally located α-cells had an irregular outline and possessed numerous relatively small membrane-bound granules with a moderate to high density core. Beta cells were larger in size and had fewer granules than of α-cells. Halo areas surrounded the moderate electron-dense granules. The polygonal ∆-cells were found in clumps throughout the islet and in between β-cells. Their granules were of moderate electron density and were tightly enclosed by a limiting membrane. Pancreatic polypeptide cells were seen associated with α and β cells. They were irregular small cells with small granules and dark cytoplasm. The juxtaposition of the endocrine and exocrine elements of the pancreas can be traced back to their embryological origin and can be also of functional significance. It facilitates the mutual functional interaction of both portions of the pancreas

RESUMEN

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