Abstract
A study of the olfactory organ, with marked observation on cellular morphology of neuroepithelium was carried out in riverine catfish Ailia coila (Hamilton, 1822) using light and scanning electron microscopy. The elongated olfactory rosette within olfactory chamber was made up of 16 ± 2 leaf lets, the lamellae which connected laterally on the longitudinal central axis. The lamella consisted of two layers of epithelium enclosing the central core which contained connective tissue stroma along with blood vessels and nerve fibres. The epithelial lining displayed unequal compactness, was comprised of sensory receptor cells, undifferentiated basal cells, secretory mucous cells and two types of supporting cells differentiated as ciliated columnar or nonciliated oval type. Olfactory cells were identified by their staining emphasis, architecture, surface feature and distribution pattern in the mucosa. The surface of sensory epithelium was embossed with structurally distinct ciliated, microvillous and rod receptor cells for procuring olfactory stimuli from aquatic surroundings. The structural composition of the olfactory organ was dissertated with chemosensory system of the fish involved.