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

Abstract

The tongue of an adult degu was examined by light and scanning electron microscopy. It consists of an apex, corpus, and radix and contains a lingual prominence. The aim of this study was to describe the course of muscle fascicles of the proper lingual muscle, the presence and nature of the lingual salivary glands, and particularly the appearance and distribution of the lingual papillae. Three major types of papillae have been observed: filiform, conical, and vallate. The dorsal surface of the lingual apex extends in caudally bent filiform papillae with two spines. The lingual corpus bears long filiform papillae with a single tip. The lingual radix contains crown-like papillae in the region of the prominence and conical papillae in the remaining areas. Two oval vallate papillae were discovered caudally on the lingual radix. This first description of the lingual structures in a degu could be used for comparative studies or as basic data for differentiation of lingual morphology in this species.

Morphology and microstructure of the tongue of the lesser bamboo rat (Cannomys badius)

“…The number of vallate papillae in rodents has been found to range from one to four. The lesser bamboo rat had two vallate papillae, similar to those in its spalacid relatives (Kilinc et al, ; Wannaprasert, ), caviids (Ciena et al, ; Emura et al, ; Santos et al, ; Watanabe et al, ) and degu (Cizek, Hamouzova, Jekl, Kvapil, & Tichy, ). Only a single papilla is observed in the mouse (Kobayashi et al, ), bank vole (Jackowiak & Godynicki, ) and lab rat (Reginato et al, ).…”

“…Weber's glands, posteriorly adjacent to Ebner's gland, deliver their products onto the surface of the lingual radix. These glands in the lesser bamboo rat were of the pure mucous type, like in the American beaver (Shindo et al, ) and large bamboo rat (Wannaprasert, ), but in contrast to the seromucous type found in the rat (Nagato, Ren, Toh, & Tandler, ), degu (Cizek et al, ) and Persian squirrel (Sadeghinezhad et al, ). Mucus is a viscous, slippery substance so it can facilitate deglutition of hard and dry food, prevent damage to the lingual epithelium and lubricate tongue movement through the intraoral structures.…”

“…These morphologies of the vallate papillae and their surroundings in the lesser bamboo rat are similar to those observed in its close relative, the large bamboo rat (Wannaprasert, ). It is noteworthy that in many rodents, such as the Patagonian cavy (Emura et al, ), agouti (Ciena et al, ), degu (Cizek et al, ) and guinea pig (Ciena et al, ), grooves bordering the vallate papillae are interrupted, forming separate parallel grooves. From an anatomical point of view, because vallate taste buds are normally buried in the papillary sidewall and their taste pores open into the trench, the vallate papilla with a complete moat perhaps provides a larger occupied area of taste buds than that of a comparable size with an incomplete moat.…”

Biological aspects of the tongue morphology of wild-captive WWCPS rats: a histological, histochemical and ultrastructural study

“…The median groove in the WWCPS was approximately 1 cm long and was found only in the apex. A similar well demarcated median groove in the region of the apex was found in rodents such as the bank vole (Jackowiak and Godynicki 2005 ), porcupine (Karan et al 2011 ), the squirrel (Ünsaldi 2010 ), agouti (Ciena et al 2013 ), hazel dormouse (Wołczuk 2014 ), the Persian squirrel (Sadeghinezhad et al 2018 ), the large bamboo rat (Wannaprasert 2018 ) and at the apex and body of the tongue in the degu (Cizek et al 2016 ). In contrast to wild rats, the median groove was absent in the guinea pig (Kobayashi 1990 ), Patagonian cavy (Emura et al 2011 ) and capybara (Watanabe et al 2013 ).…”

“…However, the majority of those studies did not assess gender differences, and differences between wild and laboratory rats. Numerous histological and histochemical studies, as well as scanning electron microscopy (SEM) and TEM, have enabled the identification of significant differences in the microstructure of the lingual surface in other selected rodents of the Rodentia order (Kobayashi 1990 ; Kobayashi et al 1992 ; Grandi et al 1994 ; Stangl and Pfau 1994 ; Whitehead and Kachele 1994 ; Watanabe et al 1997 , 2013 ; Emura et al 1999a , b , 2001 , 2011 ; Jackowiak and Godynicki 2005 ; Ünsaldi 2010 ; Shindo et al 2006 ; Kulawik and Godynicki 2007 ; Toprak and Yilmaz 2007 ; Nonaka et al 2008 ; Cheng et al 2009 ; Kilinc et al 2010 ; Alvarez et al 2011 ; Atalar and Karan 2011 ; Karan et al 2011 ; Abumandour and El-Bakary 2013 ; Ciena et al 2013 , 2017 ; Sakr et al 2013 ; Wołczuk 2014 ; Cizek et al 2016 ; Sadeghinezhad et al 2018 ; Wannaprasert 2018 ).…”