Gross Morphology of the Intra‐Oral <i>rhamphotheca</i>, Oropharynx and Proximal Oesophagus of the Emu (<i>Dromaius novaehollandiae</i>)

2012

Zoomorphology

The final publication is available at http://www.springerlink.com/content/6j37487920884049/ Abstract The tongue body of Rhea americana is triangular and partially pigmented with each caudo-lateral margin displaying a round, sub-divided lingual papilla. The tongue root is a smooth, non-pigmented tract of mucosa. The tongue body is supported by the paraglossum and distal half of the rostral projection of the basihyal (RPB), and the tongue root by the proximal half of the RPB, body of the basihyal and proximal ceratobranchials. An urohyal is absent; however, peculiar to R. americana, the caudal margin of the cricoid body displays a median projection, which may represent the remnant of the urohyal incorporated into the cricoid. The laryngeal mound is less elevated, the arytenoid cartilages are smaller than in other ratites, and the caudal margin displays pharyngeal papillae that vary in shape and number. The unique morphology of the lingual skeleton and its positioning within the tongue of R. americana, the rostral insertion of the M. ceratoglossus, the absence of the urohyal (enhanced ventroflexion) and the caudal positioning and mobile attachment of the ensheathed basihyal to the paraglossum would appear to allow independent movement of the tongue body relative to the hyobranchial apparatus. Additionally, the deeply indented base and rostral oval opening in the paraglossum limits the length of cartilage present in the midline of the tongue body. This may allow the tongue the necessary flexibility for the lingual papillae to clean the choana. The cleaning action of the tongue would occur simultaneously Communicated by T. Bartolomaeus.M. Crole ( ) • J. Soley Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa e-mail: martina.crole@up.ac.za with the previously described role of this organ and associated structures during feeding. Thus, the so-called reduced, ancestral tongue of R. americana may be structurally and functionally more complex than previously believed.

Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%

Section: Morpho-functional Considerationsmentioning

confidence: 99%

Section: Morpho-functional Considerationsmentioning

confidence: 99%

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Gross anatomical features of the tongue, lingual skeleton and laryngeal mound of Rhea americana (Palaeognathae, Aves): morpho-functional considerations

2012

Zoomorphology

“…1). The oropharynx was exposed as previously described (Crole and Soley 2010a). The interramal region was removed from the bony mandible by sharp incision following the inside mandibular edge.…”

Section: Distribution Of Taste Budsmentioning

confidence: 99%

Contrasting morphological evidence for the presence of taste buds in Dromaius novaehollandiae and Struthio camelus (Palaeognathae, Aves)

2015

Zoomorphology

This study, facilitated by the use of immunohistochemistry, indicated the presence of taste buds in Dromaius novaehollandiae but not in Struthio camelus. Seen at the light microscope level, the taste buds consisted of follicular cells and receptor cells. The follicular cells were located at the periphery of the taste bud, essentially encapsulating the receptor cells. Two morphologically distinct receptor cells were identified. Immunohistochemical labelling for neurofilament identified gustatory nerves within the taste bud. The distribution of taste buds in D. novaehollandiae matched strategic locations in the oropharynx along which food could be sampled, according to the feeding method described for these birds. Future feeding studies would be necessary in D. novaehollandiae to determine the importance of taste discrimination in their diet. This study represents the first confirmed report of a sense of taste in any ratite species.

Comparative Distribution and Arrangement of Herbst Corpuscles in the Oropharynx of the Ostrich (Struthio camelus) and Emu (Dromaius novaehollandiae)

2014

The Anatomical Record

Herbst corpuscles are widely distributed throughout the oropharynx of the ostrich and emu in contrast to the general situation in birds. Knowledge of the comparative distribution of Herbst corpuscles in the oropharynx of these two commercially important ratite species may assist in a better understanding of their feeding habits. Tissue sections representing all parts of the oropharynx of five ostrich and five emu heads collected after slaughter were prepared for light microscopy, the Herbst corpuscles counted, and the relative percentage of corpuscles calculated for defined anatomical regions. Herbst corpuscles were more widespread in the oropharynx of the emu (where they were additionally found in the tongue and laryngeal mound) than in the ostrich but were absent from the pharyngeal folds in both species. The results further indicated that Herbst corpuscles were strategically located to aid in the handling and transport of food. In this context, the high concentration of Herbst corpuscles in the prominent median palatine and ventral ridges in the ostrich denote these structures as sensory organs, namely the palatal and interramal organs. The presence of these sensory organs, coupled with the higher relative percentage of Herbst corpuscles located on the rostral oropharyngeal floor, indicate that the part of the oropharynx caudal to the mandibular and maxillary rostra forms an important sensory region in the ostrich. Additionally, speciesspecific concentrations of Herbst corpuscles within the oropharynx were identified which appear to assist in the accurate positioning of the tongue and laryngeal mound for cleaning the choana (internal nares) after swallowing.