Morfobiometria dos anéis de ossículos esclerais em Testudines

Abstract

The morphobiometric description of the scleral ossicle rings in Testudines is essential to fill the existing knowledge gaps regarding its structure, physiological and taxonomic aspects. Hence, the objective of this thesis was to perform a study of those rings through: 1 – anatomical methods using osteotechnics (maceration and diaphanization) and histological methods (HE stain and histochemistry by Masson’s Trichrome and Picrosirius Red) in 25 green turtles’ (Chelonia mydas) frozen heads for morphologic and craniometric description of the aditus orbitae and scleral rings, besides count, anatomic classification and histological description of individual ossicles; 2 – tomography and ultrasound methods performed in one green turtle (C. mydas), one black-bellied slider (Trachemys dorbigni) and one red-footed tortoise (Chelonoidis carbonarius) for anatomical description and ecobiometry of thickness, density, width and diameter of each ossicle ring’s opening. The main obtained data were: 1 - variation of ossicle count per ring (between nine and seventeen) inside the reported range for reptiles, individual ossicles with trapezoid format, average diameter of the inner opening (6.32 mm) characteristic of scotopic species, average area of the inner opening representing a maximum of 8.37% of the orbital area, proposal of two new ossicular classifications (plus-Verzahnug and minus Verzahnug), bone tissue with lamellar arrangement, which is typical of compact and resistant bones, without bone remodeling characteristics; 2 – general morphological and ring location similarities amidst the three evaluated species with some ecobiometrical differences (green turtle’s rings were visibly larger) probably due to the dissimilar animal sizes. The results may be useful for deductions regarding physiology, activity patterns, taphonomic interpretations and distinction between taxa, apart from the comprehension about homology amongst the species. Both ultrasound and computed tomography were useful tools for this research.