Morphology of the Atlantic salmon (Salmo salar)tongue

Abstract

The Atlantic salmon (Salmo salar) is a freshwater and marine rayfinned bony fish of the family Salmonidae. It is present in the northern Atlantic Ocean and in rivers flowing into the north Atlantic and following the human introduction, in the north Pacific Ocean. Even if several recovery programmes have been carried out in numerous countries, due to the habitat destruction and an uncontrolled activity of recreational and commercial fishing, the number of the wild Atlantic salmon has been significantly reduced and only 0.5% of the wild species are available in world fish markets. The rest are farmed, coming from aquaculture in Norway, Chile, Canada, the UK, etc. An excessive growth in production was revealed in the last decades, and in the next future, a further increase is expected. Regarding their nutrition, the salmon are carnivorous by nature, but in aquaculture, for the diminishing of marine resources, alternative food has been experienced being an important challenge for the industry, and protein and oil are obtained by krill, insects, bacteria and wood products (Løkka,

Anatomical, histological and immunohistochemical study of the tongue in the rainbow trout (Oncorhynchus mykiss)

“…Previous observations on the tongue of several teleosts have shown the presence of a well‐developed muscular component (Abbate et al., 2006,2017,2020a,2020b; Abbate, Guerrera, Montalbano, Ciriaco, et al., 2012; Abbate, Guerrera, Montalbano, De Carlos, et al., 2012; Guerrera et al., 2015; Levanti et al., 2017), while our results demonstrate that the rainbow trout tongue shows several types of connective tissues, with different functional properties, from the embryonal tissue, the mesenchyme, to specialized connective tissues, as cartilaginous, bone and adipose tissues, as well as dense connective tissue raised at irregular intervals to form papillae with mechanical, sensory or mechano‐sensory function. The functional properties are therefore correlated to different types of cells and fibres, present within the tissue and in the characteristics of the fundamental substance that constitutes the extracellular matrix.…”

“…Therefore, a well-developed taste is the prove that the rain- Previous observations on the tongue of several teleosts have shown the presence of a well-developed muscular component (Abbate et al, 2006(Abbate et al, ,2017(Abbate et al, ,2020a(Abbate et al, ,2020bAbbate, Guerrera, Montalbano, De Carlos, et al, 2012;Guerrera et al, 2015;Levanti et al, 2017), to food prehension. The presence of resorption channels in the F I G U R E 11 Light micrographs (Masson trichrome with aniline blue staining) of the tongue root: circular spaces, resorption channels from which bone tissue has been removed to be replaced by bone marrow, is showed, in the insert at higher magnification deeper layers of the root indicates an active process of bone remodelling.…”

“…Until the last decade, the fish tongue was mainly described as a simple thickening of the oral cavity pavement mucosa (Buddington & Kuz'mina, 2000). Several studies demonstrated in different teleosts the presence of a true tongue (Abbate et al, 2006(Abbate et al, ,2017(Abbate et al, ,2020a(Abbate et al, ,2020bAbbate, Guerrera, Montalbano, De Carlos, et al, 2012;Guerrera et al, 2015;Levanti et al, 2017;Yu et al, 2019). The morphological characteristics of the tongue in the rainbow trout match with that of other described teleost species; therefore, also in this fish of commercial interest an apex, a body and a root can be clearly showed, and these three distin- localized in all the tongue dorsal surface Abbate, Guerrera, Montalbano, De Carlos, et al, 2012;Guerrera et al, 2015), and in swordfish and Atlantic salmon, there was no evidence of them (Abbate et al, 2017(Abbate et al, ,2020a.…”

“…The fundamental role of the tongue in the mechanics of ingestion is confirmed by the presence of numerous fungiform‐like papillae, while tasting is guaranteed by several taste buds showed on the tongue mucosa, especially on the root. The capacity of tasting is variable in teleosts, in fact while in sea bass, white sea bass and sea‐bream, taste buds are widely localized in all the tongue dorsal surface (Abbate et al., 2012; Abbate, Guerrera, Montalbano, De Carlos, et al., 2012; Guerrera et al., 2015), and in swordfish and Atlantic salmon, there was no evidence of them (Abbate et al., 2017,2020a).…”

“…An important role by different hormones in feeding, related to the morphological characteristics, has been recently demonstrated in the digestive system in teleosts (Audira et al., 2018; Carnovali, Luzi, Terruzzi, Banfi, & Mariotti, 2018; Mania et al., 2017; Montalbano et al., 2016, 2018). The most of the functional processes inside the oral cavity are carried out by the tongue, whose presence and description have been showed in different species of fish, demonstrating the variation in the presence of anatomical structures like taste buds, mucous cells and teeth in teleosts, also of commercial interest (Abbate et al., 2006,2017,2020a,2020b; Abbate, Guerrera, Montalbano, Ciriaco, et al., 2012; Abbate, Guerrera, Montalbano, De Carlos, et al., 2012; Alsafy, Bassuoni, & Hanafy, 2018; Amato et al., 2012; Dos Santos, Arantes, Santiago, & Dos Santos, 2015; El Bakary, 2014; Elgendy, Alsafy, & Tanekhy, 2016; Germanà et al., 2009; Guerrera et al., 2015; Ikpegbu, Ibe, & Nlebedum, 2019; Kasumyan, 2019; Kettratad, Senarat, Boonyoung, & Jiraungkoorsku, 2017; Levanti et al., 2017; Mahmoud, Essa, & Sayed, 2016; Sadeghinezhad, Rahmati‐holasoo, Fayyaz, & Zargar, 2015; Sayed, Mahmoud, & Essa, 2019; Yu et al., 2019). Several significant papers, important as comparative data, are present in the literature in upper vertebrates like birds, reptiles and mammals (Abbate et al, 2008, 2009, 2010, 2020b; Abumandour & Kandyel, 2020; Barbosa et al., 2020; Bels et al., 2020; Cizek, Hamouzova, Goździewska‐Harłajczuk, Klećkowska‐Nawrot, & Kvapil, 2020; Cizek, Hamouzova, Kvapil, & Kyllar, 2019; Emura, 2016a,2016b,2016c,2017,2018a,2018b,2018c,2018d,2019; Erdoğan & Alan, 2012; Erdoğan & Iwasaki, 2014…”