Ultrastructural studies on the epithelia of the olfactory organ of cyprinodonts (teleostei, cyprinodontoidea)

Abstract

The epithelia of the olfactory organ of two cyprinodontoid fish species were studied both by transmission and scanning electron microscopy. The relatively flat floor of the organ is covered by sensory and nonsensory epithelia. The latter is distributed in the form of bands or ridges separating distinct areas of sensory epithelium. Differences between the olfactory organs of the two species investigated related only to the topography and quantitative distribution of the epithelia. Their ultrastructural features are very similar. The nonsensory stratified squamous epithelium contains numerous goblet cells and surface cells provided with microridges. A hypothetical function of the microridges is discussed. The sensory epithelium consists mainly of basal, supporting, and two types of sensory cells, i.e., ciliated and microvillous receptor cells. The cilia exhibitapredominant 9+0 microtubule pattern. Both epithelia are covered by a mucus layer in which all surface structures seem to be embedded. The possible nature, origin, and movement mechanisms of the mucus are discussed.

Hydrodynamic aspects of fish olfaction

“…A similar range of Reynolds numbers (0.09-0.9) may be obtained for the green swordtail from the data of Zeiske (1973) and Kux et al (1978Kux et al ( , 1988table 2); the latter range is likely to be an underestimate, however (appendix A.6.2 in the electronic supplementary material).…”

“…3 Peak velocities of flow at the entrance to the anterior nostril of these chambers have been measured by laser Doppler velocimetry (Kux et al 1978). From the anatomical data of Zeiske (1973Zeiske ( , 1974 and Kux et al (1978Kux et al ( , 1988, one can estimate the cross-sectional areas of both the anterior nostril and the olfactory lumen, and then use the principle of continuity (Vogel 1994, pp. 32-34) to estimate the average velocity of flow in the olfactory lumen.…”

“…Thus, Bashor et al (1974, p. 778) found that the velocity of a dye front moving across the surface of an excised lamella from the olfactory chamber of the longnose gar generated by the beating of cilia was between 1.5 and 2.9 mm s K1 , with an average of 2.2 mm s K1 (admittedly the olfactory lamellae of this fish have secondary lamellae). While one must be careful interpreting hydrodynamic data obtained from dye studies (Lim Later papers (Melinkat & Zeiske 1979, p. 355;Kux et al 1988, p. 258) refer to Zeiske et al (1976) Review. Hydrodynamic aspects of fish olfaction J. P. L. Cox 585 2000, p. 44), and especially in this case where the lamella was isolated, this average agrees remarkably well with a value of 1.7 mm s K1 obtained for the mean velocity of flow in the 40 mm deep gill of the blue mussel (Mytilus edulis), which is also lined with kinociliated cells ( Nielsen et al 1993, p. 61 and 70).…”

Ultrastructural characterization of the olfactory organ in glass eels,Anguilla anguilla(Osteichthyes, Anguilliformes)

“…The simultaneous presence of ciliary and microvillar cells is well established in C. auratus (Breipohl et al, 1973;Ichikawa & Ueda, 1977;Muller & Marc, 1984), in Plotosus lineatus (Theisen et al, 1991), in salmonids (Bertmar, 1973;Zielinski & Hara, 1988;Moran et al, 1992), in silurids (Caprio & Raderman-Little, 1978;Müller & Marc, 1984) and in cyprinodontids (Zeiske et al, 1976).…”

“…Of these the most noteworthy are-. 1) the conspicuous development of the cytoskeleton, whose micro-and tonofilaments abut onto the intercellular connecting junctions; 2) the multitude of electrondense granules with a putative function in secretion of mucous layer components (Zeiske et al, 1976).…”