Computed tomographic analysis of internal structures within the nasal cavities of green, loggerhead and leatherback sea turtles

Pseudopus apodus Soft Tissue Anatomy Based on Comparison of Classical Dissection and Multi-Detector Computed Tomography

Anatomy is critical for understanding the physiological and biological adaptations of living creatures. In the case of Pseudopus apodus, an anguimorph lizard belonging to the Order Squamata, it is particularly important considering the scarce previous works on the morphology of its coelomic cavity. It is interesting to consider that, over the years, using non-invasive approaches in reptiles, such as diagnostic imaging methods, is becoming popular for both scientific and clinical purposes. For the present work, we used a total of five Pseudopus apodus individuals (two males and three females); one male and one female were whole-body examined by multi-detector computed tomography (CT) and then all were dissected following a conventional anatomical protocol. The novelty and the main contribution of our multi-detector CT study is to identify structures that had never been identified before using this technique, such as the opening of the vomeronasal organ and the choanae, the tongue, the glottis, the hyoid bone, the esophagus, the stomach, the small and large intestines, the cloaca, the liver, the gallbladder, the kidneys, the ovarian follicles, the trachea, the bronchial bifurcation, the lungs, the heart, the aortic arches, the aorta, the sinus venosus, and the cranial cava veins. On the contrary, other organs like the thyroid, the pancreas, the spleen, the ureters, the urinary bladder, the oviducts, the testes, the hemipenes, the pulmonary trunk, and the pulmonary arteries were only identified in the anatomical dissection. Thus, our results demonstrate that multi-detector CT scanning is a useful tool to identify a significant number of anatomical structures in Pseudopus apodus, which is important for clinical veterinary practice related to this species or different conservation programs, among other applications.

Histological features and Gαolf expression patterns in the nasal cavity of sea turtles

Sea turtles use olfaction to detect volatile and water-soluble substances. The nasal cavity of green turtles (Chelonia mydas) comprises morphologically defined the anterodorsal, anteroventral, and posterodorsal diverticula, as well as a single posteroventral fossa. Here, we detailed the histological features of the nasal cavity of a mature female green turtle. The posterodorsal diverticulum contained spongy-like venous sinuses and a wave-shaped sensory epithelium that favored ventilation. Secretory structures that were significant in sensory and non-sensory epithelia were probably involved in protection against seawater. These findings suggested that green turtles efficiently intake airborne substances and dissolve water-soluble substances in mucous, while suppressing the effects of salts. In addition, positive staining of Gαs/olf that couples with olfactory, but not vomeronasal, receptors was predominant in all three types of sensory epithelium in the nasal cavity. Both of airborne and water-soluble odorants seemed to be detected in cells expressing Gαolf and olfactory receptors.

Anatomical Description of Rhinoceros Iguana (Cyclura cornuta cornuta) Head by Computed Tomography, Magnetic Resonance Imaging and Gross-Sections

In this paper, we attempted to elaborate on an atlas of the head of the rhinoceros iguana, applying modern imaging techniques such as CT and MRI. Furthermore, by combining the images acquired through these techniques with macroscopic anatomical sections, we obtained an adequate description of the relevant structures that form the head of this species. This anatomical information could provide a valuable diagnostic tool for the clinical evaluation of different pathological processes in iguanas such as abscesses and osteodystrophy secondary to nutrient imbalances, skull malformations, fractures, and neoplasia.

Morphological features of the nasal cavities of hawksbill, olive ridley, and black sea turtles: Comparative studies with green, loggerhead and leatherback sea turtles

We analyzed the internal structure of the nasal cavities of hawksbill, olive ridley and black sea turtles from computed tomography images. The nasal cavities of all three species consisted of a vestibule, nasopharyngeal duct and cavum nasi proprium that included anterodorsal, posterodorsal and anteroventral diverticula, and a small posteroventral salience formed by a fossa of the wall. These findings were similar to those of green and loggerhead sea turtles (Cheloniidae), but differed from those of leatherback sea turtles (Dermochelyidae). Compared to the Cheloniidae species, the nasal cavity in leatherback sea turtles was relatively shorter, wider and larger in volume. Those structural features of the nasal cavity of leatherback sea turtles might help to suppress heat dissipation and reduce water pressure within the nasal cavity in cold and deep waters.

Anatomic Interactive Atlas of the Loggerhead Sea Turtle (Caretta caretta) Head

Simple Summary

Because several diseases have been reported affecting the head of sea turtles, accurate anatomic knowledge of this body part is necessary. We provide an open access, anatomic, interactive atlas of the head of the loggerhead sea turtle (Caretta caretta), to facilitate anatomic learning using osteology, gross dissection, and computed tomography (CT) images. Using segmentation and visualization software, relevant anatomic structures were identified and colored in all images, and a computer atlas was developed. This atlas, composed of 55 images, provides an interactive anatomic resource for veterinarians, biologists, researchers, and students involved in loggerhead sea turtle conservation.

Abstract

The head of the sea turtle is susceptible to congenital, developmental, traumatic, and infectious disorders. An accurate interpretation and thorough understanding of the anatomy of this region could be useful for veterinary practice on sea turtles. The purpose of this study was to develop an interactive two-dimensional (2D) atlas viewing software of the head of the loggerhead sea turtle (Caretta caretta) using images obtained via osteology, gross dissections, and computed tomography (CT). The atlas is composed of 10 osteology, 13 gross dissection, 10 sagittal multiplanar reconstructed CT (bone and soft tissue kernels), and 22 transverse CT (bone and soft tissue windows) images. All images were segmented and colored using ITK-SNAP software. The visualization and image assessment were performed using the Unity 3D platform to facilitate the development of interactive content in 2D. This atlas can be useful as an interactive anatomic resource for assessment of the head of loggerhead sea turtles.

The nasal cavity in sea turtles: adaptation to olfaction and seawater flow

The nasal cavity of tetrapods has become phylogenetically adapted to the environment in terms of function, respiration, and olfaction. In addition, the nasal cavity of sea turtles plays an important role in seawater flow and water olfaction, unlike that of terrestrial species. Here, we describe the functional, morphological, and histological characteristics of the nasal cavity, and the odorant receptors encoded in the genome of sea turtles. The nasal cavity of sea turtles is well-suited to its complicated functions, and it significantly differs from those of other animals, including terrestrial and semi-aquatic turtles.

Behavioral effects of scents from male mature Rathke glands on juvenile green sea turtles (Chelonia mydas)

Sea turtles can detect airborne and waterborne odors, but whether they recognize scents from the same species and if so, how they affect their behavior remains unknown. The present study evaluated the behavioral effects of odorants on juvenile green sea turtles (Chelonia mydas). The odorants were derived from Rathke glands (external scent glands) of mature male green sea turtles, and from two types of food. The activity of the juveniles increased when exposed to food scents, and significantly decreased compared with controls when exposed to scents from Rathke glands. These findings indicated that scents from the same species affect behavior, and that chemical communication via olfaction has important outcomes for sea turtles.