Stichting De Traditie - SCCs
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 µm) 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 100µV 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.
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 µm) 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 100µV 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.
