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Stichting De Traditie - SCCs                




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Solitary Chemoreceptor Cells (SCC) in Fish



What are SCCs?  Fishes are equipped with 4 different chemoreceptive sensory systems: olfaction, taste, general chemoreceptive system (communis system), and solitary chemoreceptor cells (SCCs). SCCs are dispersed over the skin and have a single microvillus as detector (Mary Whitear, 1952). That is why they are also called oligovillous. They can be stained - and thus recognized - by methylene blue. They are innervated by the trigeminis nerve. Their chemoreceptive function was difficult to verify due to the small size and dispersed occurrence. There are however remarkable exceptions with respect to the distributed occurrence. SCCs occur in densely clustered packs on the anterior dorsal fin (ADF) of the rocklings Gaidropsarus sp and Ciliata sp. A relatively thick nerve runs subdermally from SCCs on the ADF to the brain. Kurt Kotrschal and Rob Peters  demonstrated that SCC respond mainly to "skin water" of other fish species by  recording electrophysiologically the nerve in unanaesthetized specimens, where functioning of the undulating ADF remained uninhibited. More reading: References/Sources

Images left:   Top: Ciliata mustela (by FAO Cimus_u0.gif). Note the position of the ADF, immediately after the first dorsal fin ray.
Middle: A photomicrograph of a taste bud (nipple like structure of about 40 Ám) on the barbel of a 1 month old specimen of Ameiurus nebulosus (Photograph Cees Eigenhuis & Jan van der Linden, 1981). The vermicular structures around the taste bud look like the oligovillous cells described by Kotrschal et al. 1984, and have about the same size.
Lower: The  30 cm long container for flow-through respiration, electrode implantation, stimulation with various chemical stimuli, and electrophysiological recording.

Image below: A paper chart recording of the gross activity of the trigeminal nerve innervating the SCCs on the ADF of Ciliata mustela after stimulation with Cottus gobio skin water (Peters et  al. 1991). Middle trace: Gross activity, scale bars 100ÁV and 1 s. Upper trace: Integration of middle trace response in arbitrary units. Lower trace: Filtered EMG in arbitrary units of the muscles of the anterior dorsal fin. Apparently motion (flickering) of the ADF is a condition for normal functioning.




scc recording


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