Données histologiques sur le tégument et les glandes épidermoïdes céphaliques des Lépidosauriens

Gabe, M.; Girons, H. Saint

doi:10.1159/000143006

Cited by 35 publications

(42 citation statements)

References 1 publication

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“…Separate ducts were shown to lead from each compartment, opening between successive serrated pleurodont teeth (Fig. 2B), making this the most structurally complex reptile venom gland described to date (9)(10)(11). Consistent with the positioning of the ducts, the teeth lack the grooves commonly associated with venom delivery in helodermatid lizards (Fig.…”

Section: Resultsmentioning

confidence: 99%

A central role for venom in predation by Varanus komodoensis (Komodo Dragon) and the extinct giant Varanus ( Megalania ) priscus

Fry

Wroe

Teeuwisse³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

130

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The predatory ecology of Varanus komodoensis (Komodo Dragon) has been a subject of long-standing interest and considerable conjecture. Here, we investigate the roles and potential interplay between cranial mechanics, toxic bacteria, and venom. Our analyses point to the presence of a sophisticated combined-arsenal killing apparatus. We find that the lightweight skull is relatively poorly adapted to generate high bite forces but better adapted to resist high pulling loads. We reject the popular notion regarding toxic bacteria utilization. Instead, we demonstrate that the effects of deep wounds inflicted are potentiated through venom with toxic activities including anticoagulation and shock induction. Anatomical comparisons of V. komodoensis with V. (Megalania) priscus fossils suggest that the closely related extinct giant was the largest venomous animal to have ever lived. evolution ͉ phylogeny ͉ squamate ͉ protein ͉ toxin P redation by Varanus komodoensis, the world's largest extant lizard, has been an area of great controversy (cf. ref. 1). Three-dimensional finite element (FE) modeling has suggested that the skull and bite force of V. komodoensis are weak (2). However, the relevance of bite force and cranial mechanics to interpretations of feeding behavior cannot be fully evaluated in the absence of comparative data. Moreover, this previous analysis did not account for gape angle, which can significantly influence results (3). Irrespective of evidence for or against a powerful bite, V. komodoensis is clearly capable of opening wounds that can lead to death through blood loss (4). Controversially, the proposition that utilization of pathogenic bacteria facilitates the prey capture (4, 5) has been widely accepted despite a conspicuous lack of supporting evidence for a role in predation. In contrast, recent evidence has revealed that venom is a basal characteristic of the Toxicofera reptile clade (6), which includes the varanid lizards (7), suggesting a potential role of venom in prey capture by V. komodoensis that has remained unexplored. This is consistent with prey animals reported as being unusually quiet after being bitten and rapidly going into shock (4) and the anecdotal reports of persistent bleeding in human victims after bites (including B.G.F.'s personal observations). Shock-inducing and prolonged bleeding pathophysiological effects are also characteristic of helodermatid lizard envenomations (cf. ref . 8), consistent with the similarity between helodermatid and varanid venoms (6).Here, we examine the feeding ecology of V. komodoensis in detail. We compare the skull architecture and dentition with the related extinct giant V. priscus (Megalania). In this 3D finite element modeling of reptilian cranial mechanics that applies a comparative approach, we also compare the bite force and skull stress performance with that of Crocodylus porosus (Australian Saltwater Crocodile), including the identification of optimal gape angle (an aspect not considered in previous nonreptilian comparative FE analyses). We als...

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Section: Resultsmentioning

confidence: 99%

A central role for venom in predation by Varanus komodoensis (Komodo Dragon) and the extinct giant Varanus ( Megalania ) priscus

Fry

Wroe

Teeuwisse³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

130

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“…Tubular lingual glands occur in a variety of reptiles [see reviews by Gabe and Saint Girons (1969) and Kochva (1978)l. According to Kochva (19781, in certain species, the deeper cells in these glands are mucous, whereas those closer to the surface are serous.…”

Section: Electron Microscopymentioning

confidence: 99%

Ultrastructure of lingual salivary glands in the American chameleon: Anolis carolinensis

Rabinowitz

Tandler

1991

Anat. Rec.

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That portion of the dorsal surface of the tongue of Anolis carolinensis that is covered by plumose papillae is underlaid by a series of tubular salivary glands that open between the papillae; glands persist into the posterior zone of the tongue, where they open between cylindriform papillae. Anterior glands are serous in nature--they consist of simple columnar epithelial cells that contain abundant secretory granules exhibiting a variety of substructural patterns. The Golgi apparatus is large and of unusual appearance, with numerous closely packed terminal dilatations and condensing vacuoles. Near the posterior border of the lingual zone covered by plumose papillae, mucous cells begin to appear in the glandular epithelium. More posteriorly, the apical portions of the glands consist entirely of mucous cells, whereas the blind ends of the glands are composed of serous cells. The most posterior glands are of the pure mucous variety. The glands finally disappear a short distance posterior to the cylindriform papillae. The functions of the abundant and highly differentiated salivary glands of the Anolis tongue remain obscure.

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“…Nearly every aspect of the venom delivery system of elapids and viperids is morphologically distinct. The extrinsic venom gland musculature (see Haas, 1973;Jackson, 2003), venom gland and venom duct (see Gabe and Saint Girons, 1967;Kochva, 1978Kochva, , 1987, maxilla and fangs (see Duvernoy, 1832;Knight and Mindell, 1994) and the venom chambers (Young et al, 2001b), all show marked morphological differences between elapids and viperids. Nevertheless, in both clades the extrinsic venom gland muscles function to raise intraglandular pressure, the venom chambers of the distal venom delivery system appear to pool venom and act as a barrier to venom flow, and displacement of the fang sheath appears to be a prerequisite to venom flow.…”

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confidence: 99%

The buccal buckle: the functional morphology of venom spitting in cobras

Young

Dunlap

Koenig

et al. 2004

Journal of Experimental Biology

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Données histologiques sur le tégument et les glandes épidermoïdes céphaliques des Lépidosauriens

Cited by 35 publications

References 1 publication

A central role for venom in predation by Varanus komodoensis (Komodo Dragon) and the extinct giant Varanus ( Megalania ) priscus

A central role for venom in predation by Varanus komodoensis (Komodo Dragon) and the extinct giant Varanus ( Megalania ) priscus

Ultrastructure of lingual salivary glands in the American chameleon: Anolis carolinensis

The buccal buckle: the functional morphology of venom spitting in cobras

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