Scanning Electron Microscopic Structure of the Lingual Papillae of the Common Opossum (Didelphis marsupialis)

Abstract

The mammalian tongue has evolved for specialized functions in different species. The structure of its papillae tells about the animal's diet, habit, and taxonomy. The opossum has four kinds of lingual papillae (filiform, conical, fungiform, vallate). Scanning electron microscopy of the external features, connective tissue cores, and corrosion casts of the microvasculature show the filiform papillae have a spearhead-like main process and spiny accessory processes around the apical part of the main process. The shape and number of both processes depend on their position on the tongue. On the apex, the main processes have shovel-like capillary networks and the accessory processes have small conical networks. On the lingual radix, the processes have small capillary loops. In the patch region, conical papillae have capillaries arranged as a full sail curving posteriorly. The fungiform papillae are scattered among the filiform papillae and have capillary baskets beneath each taste bud. Giant fungiform papillae on the tongue tip are three to four times larger than the ones on the lingual body. Capillaries of giant papillae form a fan-shaped network. The opossum has three vallate papillae arranged in a triangle. Their tops have secondary capillary loops but not their lateral surfaces. Mucosal folds on the posterolateral border have irregular, fingerlike projections with cylindrical capillary networks. These findings and the structure of the rest of the masticatory apparatus suggest the lingual papillae of opossum have kept their ancestral carnivorous features but also developed the herbivore characteristics of other marsupials.

Tongue papillae morphology of brown-throated sloth Bradypus variegatus (SCHINZ, 1825)

“…The vallate papillae in the present study were observed on the root region of the tongue, as is reported in other mammals (Qayyu et al, 1988;Pastor et al, 2008). Only two vallate papillae were observed in the distal third of Bradypus variegatus' tongue, corroborating with the results from Benetti et al (2009) in Bradypus torquatus and agreeing with what was observed in other Xenarthras, such as armadillos (Morais and Watanabe, 1988;Morais et al, 1994;Estecondo et al, 2001;Estecondo et al, 2004;Ciuccio et al, 2008).…”

“…The morphology of the tongue of the animals can suffer variations according to the taxonomy, habitat, behavior and diet (Okada and Schraufnagel, 2005). According to findings by Jackowiak and Godynicki (2004), the presence, distribution and structure of the taste buds are correlated to the feeding habits of the animal, and it can vary and suffer adaptations (Pastor et al, 2008).…”

“…According to findings by Jackowiak and Godynicki (2004), the presence, distribution and structure of the taste buds are correlated to the feeding habits of the animal, and it can vary and suffer adaptations (Pastor et al, 2008). Doran and Baggett (1971) concluded that the tongue of mammals can be divided in two functional categories, each one with a clear morphological correlation.…”

“…However, other authors suggest that these same papillae are related to the mastication process, once they increase the friction produced by the tongue during the movement and crushing of food (Pastor et al, 2008). Besides this they are also involved with the body cleaning function (Iwasaki et al, 1992) in some species.…”

Papillary architecture of the lingual surface in the puma (Puma concolor)

“…In puma, the dorsal surface of the lingual apex and body was entirely covered by filiform papillae that was reported in many carnivorous species such as bear (Pastor et al, 2011), jaguar (Emura, Okumura & Chen, 2013), ferret (Takemura et al, 2009), opossum (Okada & Schraufnagel, 2005) and fishing cat (Emura & Okumura, 2014). In the present study, filiform papillae had many secondary projections that emerged from the base of main papillae.…”