Comparative Morphology Of The Olfactory Epithelium Of Some Chinese Endemic Cyprinid And Loach Cavefish By Sem

The present research describes surface architecture of the olfactory epithelium for ninespecies: four Cyprinid cavefish, Sinocyclocheilus jii, S. furcodorsalis, S. altishoulderus and S.aluensis five loach species Oreonectes platycephalus, O. polystigmus, O. guananensis, O.macrolepis and Triplophysa dalica were studied on a Scanning Electron Microscope. The O.platycephalus and T. dalica are surface species remaining seven species are subterraneanhabitats. The cave species are living in subterranean habitats and exhibiting some degree oftroglomorphy. Closely related species troglobite furcodorsalis compared with troglophile jiispecies. Same way troglobtite altishoulderus compared with troglophile aluensis species on thebasis of surface morphology and sensory cell distributions on the surface of the olfactorylamellae. Troglobite species are quite different than troglophile species with sensory cell typesand their distributions on the surface of the lamellae. The olfactory epithelium of S. jiivisualizes two types of receptor cells (i) ciliated sensory with microvillus (ii) ciliated non-sensory cells in the form of large tufts in one direction with intermingled rod receptor cells.Indifferent finger print like microridges cells were shown with microvillus and chloride cells infish concern. Troglobite species S. furcodorsalis sensory epithelium showing interesting featurewith presence of blood cells. Most part of the lamellae is showing non-sensory epithelium withstratified ciliated non-sensory cells. Rod cells are present in the olfactory epithelium of S.furcodorsalis less than S. jii microridges with indifferent cell types and blood cells have specialinterest in this troglobite species.Sinocyclocheilus altishoulderus compared with S. aluensis troglophile on the basis ofsurface architecture of olfactory epithelium. The sensory elements in both species wererepresented by ciliated sensory cells and microvillus sensory cells; the latter showed a differentdistribution in the two species, being more numerous in S. aluensis. The non-sensory elementsin S. altishoulderus were ciliated non-sensory cells, non-sensory cells with microridges andchloride cells. Moreover, probable mast cells were visible on the surface of the epithelium.They morphologically resemble mammalian mast cells, and we suggest they could befunctionally similar to those of other vertebrates. In the olfactory epithelium of S. aluensis, onthe contrary, it was not possible to find mast cells and chloride cells and large amount of thelamellae were covered by cells with microridges and numerous mucous cells. The presence of mast cells and chloride cells in the olfactory epithelium of S. altishoulderus may have specialinterest in this species, otherwise possible differences and physiological changes of concernedspecies should be taken in account in order to explain such variability in cell types.Oreonectes platycephalus, O. polystigmus, O. guananensis and O. macrolepis, olfactoryorgans are showing sensory receptors and cell types by three patterns: two species O.polystigmus and O. guananensis are quite resembled with each other as well as distributionpatterns of cell types in the olfactory epithelium. First time horn-like structure on the olfactorylamellae was found in O. polystigmus species. Ciliated non-sensory cells with intermingledmicrovillus cells showed different distributions among all species. Supporting cells were notdetected in all studied species. The non-sensory elements in O. polystigmus and O. guananensiswere ciliated non-sensory cells, with microridges indifferent cells. The presence of chloridecells in the olfactory epithelium of O. macrolepis and O. guananensis may have special interestin these species.Triplophysa dalaica olfactory organs are oval in shape, lying in the olfactory chamberon the dorsal side of the head. Ten pairs of lamellae in the rosette are present on each side ofthe middle raphe. Lamellae are covered with cilia at some margins. The surface of the olfactorylamellae is divided into three epithelial regions: sensory, ciliate non-sensory and non-ciliatednon-sensory epithelium. Sensory epithelium consists of receptors and supporting cells, ciliatednon-sensory epithelium is covered with dense cilia and non-receptor epithelium is covered withciliated stratified epithelial cells and mucus cells. Cells other than epithelial cells present on thesurface of the rosette are related to the significant olfactory function in the fish concerned.