A novel cartilage type in the sclera of <scp><i>Chelonia mydas</i></scp>: First report

This study provides a histological description of the mucoid cartilage, a previously undescribed cartilage subtype in marine reptiles. The ocular anatomy of Chelonia mydas (green sea turtle) consists of a fibrous tunic, a vascular tunic, and a nervous tunic. The sclera is composed of a posterior cartilaginous cup and two distinct types of cartilage: hyaline cartilage externally and mucoid cartilage internally. The analysis included 50 eye globes from green sea turtles, either found dead or deceased after unsuccessful treatment. Mucoid cartilage is characterized by vascularization, low cellular density, the presence of melanocytes, and an extracellular matrix rich in Type III collagen. These findings contribute to a deeper understanding of cartilage diversity and the structural complexity of marine reptile eyes, with potential conservation implications.