Histological and ultrastructural studies of the pancreas of native rabbits (Oryctolagus cuniculus)

The pancreas of male adult native rabbit was studied by using light microscope (LM) and transmission electron microscope (TEM). The pancreas possessed both exocrine and endocrine portions. Exocrine portion included both acinar and ductal cells. The acinar cells were pyramidal in shaped which formed the lining epithelia of secretory units (acini). The apical cytoplasm of acinar cells contained unequal size and variable electron opacity of zymogen granules, while the basal part occupied by welldeveloped rough endoplasm reticulum (rER). Short microvilli projected from the free surfaces of both acinar and ductal cells. The lateral cell membranes of adjacent acinar and ductal cells adhere apically by junctional complex, which was composed of zonulae occludens and zonulae adherens. There was notable interdigitating between the lateral cell membranes of neighboring ductal cells that were located beneath the junctional complex. The oval or irregular pancreatic islets consisted of β, α and δ endocrine cells. Both βand α-cells could be demonstrated by using LM and TEM, whereas δ-cells visualized with TEM only. The cytoplasm of β-cells contained purple granules and α-cells showed yellowish granules in their cytoplasm when stained with aldehyde fuchsine method. At ultrastructure level, the cytoplasmic granules of β-cells were identified by homogenous electron dense core with clear hallo zone, the numerous granules of α-cells had very electron dense granules and δ-cells contained few granules similar to those of α-cells.βor α-cells inserted as a single cell and in a partial manner between the ductal cells of some ducts.