Abstract :
Introduction: Proliferation of bile duct-like structures is a hepatic cellular reaction observed in most forms of human liver diseases and in a variety of experimental conditions associated with liver injury and hepatic regeneration. However, the origin, ultrastructural features, means of initiation, and significance of this type of hyperplasia are unknown yet. Aim of the Work: The present study aims to clarify and evaluate the ultrastructural characteristics of the ductular epithelium-like cells and structures which proliferate after chronic exposure to electromagnetic field (EMF). Materials and Methods: Sixteen adult male albino rats (Rattus norvegicus) were utilized to study the effects of EMF equaling 2 ml tesla, on the proliferation of periportal biliary epithelial cells. Magnetic exposure was applied for 60 minutes for 3 days per week for two weeks. Results: The ultrastructural observations showed that the bile duct epithelium-like structures appeared consisted of cells like the bile duct cells with characteristic microvilli, tight junctions and desmosomes. Basal lamina was observed surrounding the bile ductular cells. Each cell clearly established the presence of numerous mitochondria, pinocytic vesicles, tonfilaments, large nucleus and scanty lucent cytoplasm. Small hepatocytes, fibroblasts and collagen fibres were commonly observed in close proximity to the region of the developed ductular structures. Conclusion: The proliferated bile duct-like cells and structures might represent products of the extant biliary epithelium that contribute in retaining its characteristics. Besides, it acts as a transitional structure that develop in the periportal areas of regenerating hepatic nodules, serving as precursors of bile duct and/or hepatic cells. Hence, it seems to represent hepatic stem-like cells.
