Structural and ultrastructural features of the agouti tongue (Dasyprocta aguti Linnaeus, 1766)

Abstract

The agouti (Dasyprocta aguti Linnaeus, 1766) is a wild rodent belonging to the family Dasyproctidae that is found throughout Brazil and feeds on fruits and seeds. The aim of the present study was to describe the following features of the tongue of agouti: its morphological structures, the three-dimensional characteristics of the lingual papillae surface, the connective tissue cores (CTCs) and the epithelial cell ultrastructure. Four types of papillae were observed on the dorsal surface of the tongue with a triangular shape: filiform, fungiform, foliate and vallate. Filiform papillae were distributed throughout the tongue surface, and removal of the epithelial surface revealed conical CTCs and multifilaments. Fungiform papillae were observed in the rostral and middle regions, whereas foliate papillae developed in pairs on the lateral margin of the caudal region. Removal of the epithelium in these regions revealed CTCs with parallel laminar conformation. Vallate papillae were arranged in a V-shape in the caudal region, and their CTCs ranged in shape from elongate to ovoid. The ultrastructural components of the dorsal epithelium were the basal, spinous, granular and keratinised layers. A broad area with cytoplasmic projections was identified in the interface region between the lamina propria and the basal layer. Flattened cells with intermediate filaments were observed in the transitional region between spinous and granular layers. The keratinised layer was composed of superimposed epithelial cells where desmosomes and cell-surface microridges were observed. These structural features, including the three-dimensional aspects of the lingual papillae, the CTCs and the epithelial ultrastructure, indicate that when compared with other animals, particularly other rodent species, the morphological features of the tongue of agouti are relatively well developed, especially regarding foliate and vallate papillae.

Light and scanning electron microscopy of the tongue of a degu (Octodon degus)

“…The lingual prominence was formed similarly as in the agouti (Ciena et al 2013), Middle East blind mole rat (Kilinc et al 2010), Patagonian cavy (Emura et al 2011), American beaver (Shindo et al 2006), bank vole (Jackowiak ans Godynicki 2005) and porcupine (Atalar and Karan 2011). Compared to these species, an inconspicuous lingual prominence was described in the Manchurian chipmunk (Kobayashi et al 1992).…”

“…The tongue of the degu was wedge-shaped as in the agouti (Ciena et al 2013) and porcupine (Atalar and Karan 2011). The lingual prominence was formed similarly as in the agouti (Ciena et al 2013), Middle East blind mole rat (Kilinc et al 2010), Patagonian cavy (Emura et al 2011), American beaver (Shindo et al 2006), bank vole (Jackowiak ans Godynicki 2005) and porcupine (Atalar and Karan 2011).…”

“…Vallate papillae have not been revealed in the tongue of the guinea pig, Cavia porcellus (Sakr et al 2013). The taste buds have been described in various rodents Ciena et al 2013;Kubota and Togawa 1966;Atalar and Karan 2011;Unsaldi 2010). There have also been studies that have described the lingual glands (Nagato et al 1997;Shindo et al 2006;Ciena et al 2013).…”

“…Filiform, fungiform, vallate and foliate papillae have been found in the agouti, Dasyprocta aguti (Ciena et al 2013), capybara, Hydrochaeris hydrochaeris , American beaver, Castor canadensis (Shindo et al 2006), nutria, Myocastor coypus (Emura et al 2001), large vesper mouse, Calomys callosus (Watanabe et al 1997), porcupine, Hystrix cristata ) and Japanese dormouse, Glirus japonicus (Kubota and Togawa 1966). Foliate papillae were absent in the Middle East blind mole rat, Spalax ehrenbergi (Kilinc et al 2010), Japanese grass vole, Microtus montebelli (Emura et al 1999) and squirrel, Sciurus vulgaris (Unsaldi 2010).…”

“…Scanning electron microscopic studies of the tongue have already been performed on agouti, Dasyprocta aguti (Ciena et al 2013), capybara, Hydrochaeris hydrochaeris , Patagonian cavy, Dolichotis patagonum (Emura et al 2011), nutria, Myocastor coypus (Emura et al 2001), large vesper mouse, Calomys callosus (Watanabe et al 1997), porcupine, Hystrix cristata (Atalar and Karan 2011), Middle East blind mole rat, Spalax ehrenbergi (Kilinc et al 2010), house-mouse, Mus musculus (Kobayashi et al 1989), Manchurian chipmunk, Tamias sibiricus (Kobayashi et al 1992), Japanese grass vole, Microtus montebelli (Emura et al 1999), guinea pig, Cavia porcellus (Sakr et al 2013), American beaver, Castor canadensis (Shindo et al 2006), hazel dormouse, Muscardinus avellanarius (Wolczuk 2014).…”