Gross and microscopic observations on the lingual structure of the franciscana (Pontoporia blainvillei — gervais and d'orbigny, 1844)

Abstract

In most anatomical studies developed with mammals, the tongue is described as highly differentiated among different species. However, studies on the tongue of aquatic mammals are still limited as compared to those on terrestrial mammals. The aim of this study was to describe the tongue morphology of the Franciscana dolphin (Pontoporia blainvillei) using macroscopic observations, light, and scanning electron microscopy. Microscopically, the dorsal surface was covered by a keratinized stratified epithelium. Salivary gland acini were found on the middle and caudal third of the tongue. The dorsal surface was totally covered by filiform papillae with a connective tissue core and a connective tissue structure round in shape in the middle and caudal regions.

Nature or Nurture: Is the Digestive System of the Pontoporia blainvillei Influenced or Determined by Its Diet?

“…In the present work, the average number of marginal papillae was 3 in adults, 30 in juveniles, and 50 in neonates. These data are consistent with those of Guimaraes et al [41], who obtained an average number of marginal papillae of 53 in immature and 36.7 in mature dolphins and only 3.75 on average in adults (being nonexistent in some specimens), but they differ from the 13 to 15 projections counted in juveniles by Yamasaki et al [38], which was probably measured in older juveniles.…”

“…Even as we have described in the Franciscana, these papillae tend to be reduced or disappear with age, although they may persist in some individuals [ 26 ]. From the age of two months, this species begins to consume solid food and its feeding becomes mixed, and then these papillae assist in holding the prey against the palate while water flows through the papillae [ 33 , 34 , 36 , 39 , 41 ] until they begin to involute due to disuse and completely lose functionality in adulthood.…”

The Orexin System in the Enteric Nervous System of the Bottlenose Dolphin (Tursiops truncatus)

“…cetaceans have no gallbladder). However the whole organization of the gustatory sense is poorly understood: odontocetes have no sense of smell and the tongue of adult dolphins possesses few or no taste buds [2] . Muscular species of fish and cephalopods living in the proximity of the continental shelf are among the favorite prey of bottlenose dolphins [3] ; captive bottlenose dolphins are known to prefer capelin ( Mallotus villosus ) and other fish with a relatively high content of water, especially during the warm season [4] .…”