Acinar cells that located near the islets of Langerhans (juxta or peri-insular acinar cells) differ from those lying at a certain distance from the islets (tele-insular acinar cells). The present investigation was conducted to reveal the morphological differences between peri and tele-insular acinar cells in the pancreas of Gecko, Tarentola annularis using light and electron microscopes and to evaluate the relationship between endocrine and exocrine pancreatic tissues. Histological examination of the exocrine pancreatic tissue revealed a clear zymogen halo or zymogen mantle around the islet cells. Ultrastructural examination showed that peri-insular cells around the islets of Langerhans display considerable synthesizing activity than those cells in the tele-insular region. In the peri-insular region, the pancreatic acinar cells are morphologically differentiated into three types; dark, light, and centroacinar cells. Dark acinar cells are the most common cells in this region. They have well-developed rough endoplasmic reticulum, well developed Golgi apparatus, large number of mature zymogen granules, and euchromatic nuclei. In the tele-insular region, only two types of acinar cells are detected; dark acinar and centroacinar cells. Dark acinar cells have flattened form of rough endoplsmic reticulim cisternae with the prevalence of the vesicular form of rough endoplasmic reticulum. Reduced Golgi apparatus, small numbers of mature secretory granules, and heterochromatic nuclei. The present work indicated that exocrine parenchyma is under the influence of islets hormones and that both the pancreatic exocrine and endocrine tissues form closely an integrated organ.
Acinar cells, halo phenomena, pancreas, ultrastructure, Gecko