The olfactory epithelium of Wallago attu has been studied with conventional histological techniques. The elongated olfactory rosette consists of 62 to 64 primary lamellae in each left and right rosette. The olfactory lamellae are arranged in two rows on either side of the long raphe. Each olfactory lamella consists of two layers of epithelium separated by central core. The olfactory epithelium in one side consists of mixed sensory and non-sensory epithelium while the other side consists of non-sensory, non-ciliated flattened epithelial cells. The sensory epithelium in this fish contains receptor cells, ciliated supporting cells, basal cells, mast cells and labyrinth cells. The non-sensory epithelium is composed of ciliated supporting cells, labyrinth cells and mucous cells. Different cells of the olfactory epithelium have been correlated with the functional significance of the region concerned in the fish studied.
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