Fine structural characterization of the olfactory epithelium and its response to divalent cations Cd2+ in the fish Alburnus alburnus (Teleostei, Cyprinidae): a scanning and transmission electron microscopic study.

The olfactory organ of the fish Alburnus alburnus consists of 22 lamellae arranged into rosette like structure and are built up by supporting, gland, basal, ciliated and unspecialized epithelial cells, as well as receptor cells with microvillous, ciliated or rod shape dendritic endings. The spatial distribution of the supporting and gland cells can be considered homogeneous while the ciliated epithelial cells are dominant on the latero-marginal areas of the lamellae with a 10 +/- 3/1000 microns 2 average density. The occurrence frequency of the ciliated receptor cells is the highest in the medial area with a 30 +/- 6/1000 microns 2 average density while the microvillous receptor cells have the highest occurrence frequency in the dorso-marginal area of the olfactory lamellae with a 25 +/- 15/1000 microns 2 average density. Rod shape sensory dendrites were detected with a negligible density. The presence of divalent cations Cd2+ in the environment significantly increased the density of rod shape sensory dendrite 19.8 +/- 7.7/1000 microns 2. These results demonstrate that the appearance and composition of the population of sensory dendrites on the olfactory lamellae are affected by environmental factors.