Morphological and scanning electron microscopic studies of the tongue of the Egyptian fruit bat (Rousettus aegyptiacus) and their lingual adaptation for its feeding habits

Abstract

This study was carried out on the tongues of 12 adult normal healthy Egyptian fruit bats of both sexes. The tongue is protrusible, elongated flat with a rounded apex and its wide and thickness increase gradually toward the lingual root. There are four types of lingual papillae; two mechanical and two gustatory. The tongue divided into three parts (anterior, middle and posterior), each part subdivides into three regions; two lateral regions and median region, in addition to the lingual apex to the anterior region. The lingual papillae close to the median region of the tongue were posteriorly directed toward the pharynx, while theses present on the lateral regions of the tongue are directed medioposteriorly. There are sex subtypes of the filiform papillae; three on the anterior part (small, conical and giant), two on the middle part (cornflower and leaf-like papillae) while the posterior part contain rosette shape filiform papillae, in addition to transitional papillae and conical papillae. Two gustatory papillae represented by; small number of fungiform papillae which scattered among the filiform papillae on lingual apex and two lateral regions of the anterior and middle part of tongue, while the three circumvallate papillae on the posterior part were arranged in a triangle form.

Morphological Comparison of the Filiform Papillae of New Zealand White Rabbits (Oryctolagus cuniculus) as Domestic Mammals and Egyptian Fruit Bat (Rousettus aegyptiacus) as Wild Mammals Using Scanning Electron Microscopic Specimens

“…In the present study, the Egyptian fruit bat was characterized by elongated protrusible tongue with round long free anterior part to facilitating the movement of tongue while swiping the extracts of fruit pulp, agree with (Birt et al, 1997;Abumandour & El-Bakary;Mqokeli & Downs, 2012), while the New Zealand white rabbit tongue is characterized by elongated non-protrusible tongue with thin round apex to be adapted for eating form the ground as in; rabbit (Ojima et al, 2000), Japanese Badger (Yoshimura et al, 2009). …”

“…As in the previous published data, the lingual papillae were species-specific, in which differing in their number among mammalian species, these differences may depend on dissimilarities in diet, feeding habits and handling of food in mouth (Emura et al, 2002b;Abumandour & El-Bakary), the previous data clear in; our study in Egyptian fruit bat, this confirmed by presence of four types of lingual papillae; two mechanical and two gustatory as noted in; bats (Selim et al, 2008;Abumandour & El-Bakary;Abayomi et al, 2009), moreover other mammals have four lingual papillae; as in our study in New Zealand white rabbits; one mechanical (filiform) and three gustatory (fungiform, foliate and circumvallate) as noted in; rats (Nasr et al, 2012), bank vole (Jackowiak & Godynicki, 2005), dog and fox (Emura et al, 2006). However, three types of lingual papillae; one mechanical (filiform) and two gustatory (fungiform and circumvallate) as noted in; bats (Pastor et al, 1993;Emura et al, 2001b;Park & Lee, 2009;Masuko et al, 2007), however, there were two types only of papillae (filiform and fungiform) in hematophagous bats (Masuko et al).…”

“…The distribution of the different papillae on the various surfaces of the tongue is characteristic of a genus and may even be distinctive among different species. One of the elements that contribute most to the morphological, distribution, and type of papillae is the diet (Pastor et al, 2008;Abumandour & El-Bakary).…”

“…The reasons for this morphological diversity are generally the result of different strategies for capturing and manipulating food, grooming, or vocal modulation. The tongue is a taste organ in the buccal cavity and with its species-specific lingual papillae on the dorsal surface plays an important role in food intake, digestion in many mammals (Iwasaki, 2002;Kobayashi & Shimamura, 1982;Abumandour & El-Bakary, 2013;Pastor et al, 1993).…”

“…Previous studies on the distribution of lingual papillae on the dorsal surface of the tongue in the Egyptian fruit bat indicated its considerable species-specific character, resulting from the adaptation of the lingual mucosa to the intake of liquid and semi-liquid food (Jackowiak et al, 2009;Emura et al, 2012;Trzcielinska-Lorych et al, 2009;Abumandour & El-Bakary, 2013). The arrangement and structure of the mechanical lingual papillae, aiding the transfer of food, documented in vertebrates, constitutes general traits typical of individual taxonomic units, for example, orders or families (Azalli et al, 1991;Emura et al, 2002b;Emura et al, 2000;.…”