Light and Scanning Electron Microscopic Study of the Tongue in the Estuarine Dolphin (Sotalia guianensisvan Bénéden, 1864)

Abstract

The importance of the tongue during feeding, and the limited information on the tongue of most aquatic mammals led us to investigate its morphological aspects in sexually immature and mature Sotalia guianensis. Six tongues were measured and photo-documented after their removal from the oral cavity. The samples were divided into rostral, middle, and caudal regions, and examined using light microscopy and scanning electron microscopy (S.E.M.). Sotalia guianensis tongue presented lateral grooves from the apex to the middle portion, while the anterolateral region presented marginal papillae. Histological characteristics revealed the presence of a keratinized stratified epithelium, salivary glands in the middle and caudal portions of the tongue, and filiform papillae in the caudal region. S.E.M. images revealed the presence of filiform papillae and ducts of salivary glands in the middle and caudal portions of the tongue. We can conclude that the characteristics found in this study may reflect an adaptation to changes in diet after weaning.

Macroscopic and microscopic analysis of the tongue of the common opossum (Didelphis marsupialis)

“…The diet of a widely distributed species may vary between different biomes or habitats (Lessa and Geise, 2010). The distributions of the fungiform and filiform papillae observed in this study are similar to those described (Chamorro et al, 1987) 1 2 1 1 6 1 2 Zaedyus pichiy (Ciuccio et al, 2008) 1 2 2 1 2 2 2 Tayassu pecari (Watanabe et al, 2009) 1 2 2 1 2 2 2 Dasypus hybridus (Ciuccio et al, 2010) 1 2 2 1 2 2 2 Sotalia guianensis (Guimarães et al, 2011) 1 2 1 2 2 2 2 Saimiri sciureus (Branco et al, 2011) 1 2 2 1 1 1 2 Callithrix penicillata (Branco et al, 2012) 1 2 2 1 3 2 2 in species with different feeding habits, such as rabbits, cats, horses, llamas, rats, armadillos, peccaries, and primates (Abreu et al, 2006;Banks, 1991;Branco et al, 2011Branco et al, , 2012Chamorro et al, 1987;Ciuccio et al, 2008Ciuccio et al, , 2010Martinez et al, 1998;Watanabe et al, 1988Watanabe et al, , 2009 (Table 2). The marginal fungiform papillae surrounding the posterolateral folds and tongue tip are unique to opossums and have not been described in other land mammals.…”

“…The marginal fungiform papillae surrounding the posterolateral folds and tongue tip are unique to opossums and have not been described in other land mammals. Aside from opossums, marginal papillae have only been described for Guiana dolphins (Sotalia guianensis) (Guimarães et al, 2011). The D. marsupialis tongues examined in this study also exhibited some unique features that have not been described for other opossum species (Krause and Cutts, 1982;Martinez et al, 1998).…”

Gross and microscopic observations on the lingual structure of the franciscana (Pontoporia blainvillei — gervais and d'orbigny, 1844)

“…Our findings revealed the presence of small duct openings of the lingual glands on the dorsal surface, which is in accordance with findings of Yamasaki et al (1976) and Guimarães et al (2011). Samples from the middle and caudal third were examined histologically and salivary glands beneath the connective tissue layer were observed.…”

“…Using polarized light microscopy, the samples stained with picrosirus revealed collagen fibers of Type I and III in the projections of connective tissue like those found in the tongue of rabbits (Silva, 1999), maned sloths (Benetti et al, 2009), and estuarine dolphin (Guimarães et al 2011). These types of collagen fibers were found by Bezerra (1979) in the dermis of mammals.…”

“…It was covered by a keratinized stratified epithelium. Despite the tongue morphology of mammals being related to their life style, stratification and keratinization are basic and common characteristics of the tongue epithelium in most species of terrestrial (Benetti et al, 2009;Erdunchaolu et al, 2001;Silva, 1999;Watanabe et al, 1992) and aquatic mammals (Guimarães et al 2011;Levin and Pfeiffer, 2002;Yoshimura et al, 2002). Shimoda et al (1996) reported a nonkeratinized stratified epithelium in the tongue of Sea Otter (Enhydra lutris).…”