Indagine stutturale sulla volta della cavità orofaringea di trota iridea (Salmo Gairdneri): Distribuzione e morfologia dei bottoni gustativi

The number, morphology and anatomical distribution of the taste buds in the arch of rainbow trout (Salmo gairdneri) oro-pharyngeal cavity were analysed. This latter is constituted from a cranial (palate) and a caudal portion (pharynx). The histological observation on serial sections from the two portions allowed to clarify the oro-pharyngeal cavity structural organization. Morphometrical analyses on the taste buds number and distribution were also performed. Taste buds are localised mainly in the cranial portion of palate and in the caudal portion of the pharynx; in this latter portion the palatin organ is also located. On the palatin area, taste buds exceed the epithelial surface with their apical portion and therefore they may be referred to those reported as type I and II. On the contrary, pharyngeal taste buds, remain mostly confined in the epithelial level and so they may be referred to those defined as type III. Taste buds are located on elevated papillae, which are expansions of the mucosal lamina propria. They result separated from the epithelium by surrounding flattened marginal cells. On semi-thin sections taste buds result structurally composed by basal cells, light and dark sensorial cells. Their number and distribution are strictly related to the trout habitat and its feeding habits.