ABSTRACT
In fish, gustation takes place predominantly in the taste buds (TBs) situated around the mouth, in the oropharyngeal cavity, on the basal parts of the gills, and often also on the skin and its appendages also by means of sensory microvilli protruding above the epithelium (Whitear, 1971; Gomahr et al., 1992; Hansen and Reutter, 2004). The signals from these organs are transferred from the mouth to the brain via the facial (VII, cranial) and glossopharyngeal (IX, cranial) nerves, and from the middle and posterior part of the oral cavity by the vagus (X, cranial) nerve (for references, see Reutter and Witt, 1993). For instance, the cytology ofTBs has been studied in carp (Hirata, 1966), catfish (Reutter, 1971, 1978; Grover,Johnson and Farbman, 1976; Kapoor and Finger, 2003), blenniid and gobiid fishes (Fishelson and Delarea, 2004a), cardinal fish (Fishelson et al., 2004b), flatfishes (Tsura and Omori, 1976), rainbow trout (Ezeasor, 1980), minnow (Kiyohara et al., 1980), poeciliids (Reutter, 1973; Reutter et al., 1974), lungfish (Reutter, 1991) and in holostean fishes (Reutter et al., 2000). Fish gustation has been summarized in articles by Atema (1971), Kapoor et al. (1975), Caprio (1984), Hara (1993), Zaccone et al.,
2001 and in books by ·Beidler (1971), Hara (1992), Finger et al. (2000) and Doty (2003). It is generally accepted that there are three basic types of TBs in fishes. These are up to 100 JJ.m high and have a diameter of 50-80 JJ.m at the base, and 3.5-5.0 JJ.m at their exposed receptor area. Here they possess receptor microvilli that extend above the epithelium's surface. Type I and II TBs are raised on papillae, while the receptor areae of Type III TBs are in level with the epithelium (Reutter, 1973; Reutter et al., 1974; for references, see Hansen and Reutter, 2004).
