Functional Role of the Rodlet Cell and Macrophage in Neural Protection of the Olfactory Neuroepithelium in a Teleostean: Gobiid (Pseudapocryptes lanceolatus [Bloch and Schneider, 1801]): An Ultrastructural Study

BACKGROUND: Neural protection of the olfactory epithelium against pathogenic invasion is still hardly addressed in fish chemosensory research. AIMS AND OBJECTIVES: The ultrastructural detail on the rodlet cell and macrophage has been studied within the olfactory neuroepithelium of Pseudapocryptes lanceolatus to correlate their role in the neural protection of the chemosensory system. MATERIALS AND METHODS: The cellular structures were examined under light microscope (LM: Primo Star; Carl Zeiss Microscopy, GmbH, Germany) and transmission electron microscope (Morgagni 268D). RESULTS: Three distinct stages of the rodlet cell (viz., immature, mature, and degenerative) and macrophages have been characterized at the various depths of the olfactory neuroepithelium in P. lanceolatus. The cytoarchitecture of degenerative rodlet cell indicates holocrine mode of secretion against pathogenic invasion into the nasal cavity. Macrophages possess prominent pseudopodia, extending toward invading pathogens. The interaction between macrophage and invading pathogens implicates the role of macrophage as a scavenger to eliminate the pathogens by phagocytosis from the neuroepithelial system. CONCLUSION: This study denotes a significant difference in the mode of action of rodlet cell and macrophages, but they are commonly involved in cell-mediated nonspecific immune response against the invading pathogens.