Angioarchitectural classification of the fungiform papillae on the dorsal surface of the bullfrog tongue

Frog tongue surface microstructures: functional and evolutionary patterns

Frogs (Lissamphibia: Anura) use adhesive tongues to capture fast moving, elusive prey. For this, the tongues are moved quickly and adhere instantaneously to various prey surfaces. Recently, the functional morphology of frog tongues was discussed in context of their adhesive performance. It was suggested that the interaction between the tongue surface and the mucus coating is important for generating strong pull-off forces. However, despite the general notions about its importance for a successful contact with the prey, little is known about the surface structure of frog tongues. Previous studies focused almost exclusively on species within the Ranidae and Bufonidae, neglecting the wide diversity of frogs. Here we examined the tongue surface in nine different frog species, comprising eight different taxa, i.e., the Alytidae, Bombinatoridae, Megophryidae, Hylidae, Ceratophryidae, Ranidae, Bufonidae, and Dendrobatidae. In all species examined herein, we found fungiform and filiform papillae on the tongue surface. Further, we observed a high degree of variation among tongues in different frogs. These differences can be seen in the size and shape of the papillae, in the fine-structures on the papillae, as well as in the three-dimensional organization of subsurface tissues. Notably, the fine-structures on the filiform papillae in frogs comprise hair-like protrusions (Megophryidae and Ranidae), microridges (Bufonidae and Dendrobatidae), or can be irregularly shaped or absent as observed in the remaining taxa examined herein. Some of this variation might be related to different degrees of adhesive performance and may point to differences in the spectra of prey items between frog taxa.

Angioarchitectural form, functional distributive pattern and classification of the fungiform papillae on the crossbred Japanese cat tongue anterodorsal surface in scanning electron microscopic specimens

The purpose of this study was to undertake a three-dimensional comparative observation of the angioarchitectural form, functional distributive pattern, and to classify the fungiform papillae (FuP) found sporadically and geometrically on the oblique lines of the filiform papillae (FiP) on the entire dorsal surface of the crossbred Japanese cat foretongue in microvascular cast specimens (MVCS). By means of the corrosive resin casting technique, the MVCS of the FuP of the cat tongue were prepared and examined in detail under the scanning electron microscope (SEM). With regard to the arrangement of FiPs and FuPs on the frontal half of the antero-dorsal surface of the cat foretongue, FiP types I-V and FuP types I-IV are arranged a A form with the point in the direction of the apex and in an oblique line running from the antero-central portion to both postero-peripheral portions. In the rear half of the antero-dorsal surface of the foretongue, FiP types I-V and types FuP I-IV are arranged in a V form with the point in the direction of the radix and in an oblique line running from both antero-peripheral portions to the postero-median portion or towards the pharynx on the anterior centro-dorsal surface of the cat foretongue. With the FuP arranged in the medial zone (M) and peripheral zone (P) running from the central to the apical parts, both the peripheral parts and the pharyngeal can be classified into four types (FuP types I-IV) according to the shape and size of the main process (MP), the number of the accessory processes (AP) and the regional position of the lozenge arrangement. FuP Types I-III consisted of a MP containing a large half oval, network-like process, and the AP contained a bundle of spine-like processes arranged radially in a circle at the anterior basal margin of the MP. The FuP Type IV was made up of only one MP. In the central zone (C) of a lozenge part arranged in the A and V forms, there was no FuP as a taste organ. It was assumed that in the lozenge arrangement of the A and V forms, except for the C zone, FuPs could be classified into four types (FuP types I-IV) from the frontal portion of the antero-dorsal surface toward the pharynx on the foretongue, and would play an assistant functional role in receiving the sense of taste of foods and liquids.

Quantitative and distributive study of the fungiform papillae in the cat tongue in microvascular cast specimens

The number of fungiform papillae (FuP) has been counted, and distribution has been observed on the tongue of 55 adult cats. FuP were sampled from the whole region of the tongue surface, and the number and variation in distribution were determined in microvascular cast specimens (MVCS) of four types of FuP (Ojima et al. 1996) by scanning electron microscopy (SEM). There were approximately 35 (female) and 42 (male) FuP (mean number 38) on the whole tongue dorsal surface. FuP were most numerous in the peripheral region, and the number tended to decrease progressively from the peripheral to the medial region. There were no FuP in the central region of the tongue, in which there were types I and II filiform papillae (FiP) (Ojima and Lowe 1995). Their number differed significantly between the sexes and the regions.