Structural aspects of an unusual choroidal polarized hyaline cartilage in the eyeball of Bufo ictericus and Rana catesbeiana (Amphibia, Anura): morphological and physiological significance

Amphibian eyes play an important role in vision and in several physiological processes, such as food capture and breathing. To maintain the integrity of the eyeball there is a unique cuplike hyaline cartilage as a supporting tissue. In Bufo ictericus and Rana catesbeiana the cartilage layer is located between the retina and the choroids, being designated as choroidal cartilage, important to visual performance. On the retinal surface, there is no perichondrium, and the pigmented epithelium exhibits an intimate relationship to the cartilage layer.