Surface ultrastructure of the olfactory epithelium of loach fish, Triplophysa dalaica (Kessler, 1876) (Cypriniformes: Balitoridae: Nemacheilinae)

The olfactory organs of loach Triplophysa dalaica were examined under a scanning electron microscope, sampled from the Dali-Nor Lake, Inner Mongolia, China. The olfactory organs are oval in shape, lying in the olfactory chamber on the dorsal side of the head. Ten pairs of lamellae in the rosette are present on each side of the middle raphe. Lamellae are covered with cilia at some margins. The surface of the olfactory lamellae is divided into three epithelial regions: sensory, ciliate non-sensory and non-ciliated non-sensory epithelium. Sensory epithelium consists of receptors and supporting cells, ciliated non-sensory epithelium is covered with dense cilia and non-receptor epithelium is covered with ciliated stratified epithelial cells and mucus cells. Cells other than epithelial cells present on the surface of the rosette are related to the significant olfactory function in the fish concerned.