Light and scanning electron microscopy study of the olfactory organ of Milkfish, Chanos chanos

Abstract

This study investigates the ultrastructural and histological organization of the olfactory organ in milkfish (Chanos chanos). The olfactory rosette is fan-shaped and consists of 26-28 lamellae radiating from a central raphe located on the floor of the nasal chamber. Each lamella contains a connective tissue core covered by a two-layered epithelium composed of sensory and non-sensory regions. The sensory epithelium, located on the dorsal lamellar processes and the apical regions of the lamellae, contains three types of olfactory receptor neurons: ciliated, microvillous, and rod cells. The non-sensory epithelium, distributed along the basal, median, and outer regions of the lamellae, comprises mucous, chloride-like, lymphatic, basal, and supporting cells (both ciliated and non-ciliated). The stratified epithelial cells of the central raphe are densely packed and exhibit prominent microridges. The structural organization of the olfactory mucosa indicates a high degree of functional specialization associated with chemoreception in aquatic environments.