CT Anatomy of the Lower Respiratory Tracts of the Testudo graeca

The respiratory system of Testudo graeca (spur-thighed tortoise) has not been fully explored, especially when it comes to the detailed structure of the lungs and bronchi. Understanding these anatomical features, along with how they change when the tortoise repositions its body, is important for both studying reptile biology and for clinical practices.

In this study, we used high-resolution computed tomography (CT) to examine the trachea, bronchi and lungs of T. graeca. The tortoises were scanned in two different body positions: When their head, neck and limbs were retracted inside the shell (flexed), and when these body parts were extended outside the shell. We measured key anatomical features such as lung volume, lung dimensions (length, width and height), bronchial structure and parenchymal thickness.

CT imaging provided detailed views of the lung and bronchial structures. We found that the lungs of T. graeca are divided into distinct lateral and medial sections, with the bronchi branching into secondary bronchi that supply these areas. When the head, neck and limbs were retracted inside the shell, lung volume decreased, primarily in the cranial portion of the lungs. However, the overall lung shape, the branching of the bronchi and the thickness of the lung tissue remained unchanged between the extended and retracted positions. The bifurcation of the trachea and the orientation of the bronchi were consistent in both postures.

This study provides a comprehensive description of the lung and bronchial structures in T. graeca. It also shows that while retracting the head, neck and limbs affects lung volume, it does not significantly alter lung morphology or bronchial structure. CT imaging proved to be an effective, non-invasive method for studying the respiratory system in turtles, especially considering the challenges of accessing their internal structures. These findings offer important information that can guide future studies on respiratory adaptations in reptiles and support their clinical management.