Resumo:
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.
