Ahistological study of the corneosclera layer (Fibrous tunic) of ostrich (Struthio camelus)

BACKGROUND: The Ostrich is an interesting subject concerninganimal evolution and morphology studies. It has been speculatedthat ostrich eyes would have distinct tissue structures and this hasnot been previously studied in detail. OBJECTIVES: The aim of thepresent study was to investigate the histology of the outer layer ofthe ostrich. METHODS: Ten mature ostriches were chosen from anostrich breeding center in Jupar, Kerman, Iran. All of them were ina good shape and healthy condition. After slaughter, their headswere kept in 10 % formalin solution for 7 days and then the eyes wereremoved. Routine histological techniques were done and 6-μmthicksections were cut. Sections were stained with standardhematoxylin and eosin (H&E) and Masson's trichrome and PAS.The sections were studied under a light microscope. RESULTS:Thecornea of ostrich had both dermal and sclera components and thetwo distinct parts were separated by a distinct zone; in addition, thesclera was divided into an episclera zone and a sclera proper zone.CONCLUSIONS: The outer layer of the episclera composed ofconnective fibers loosely attached to the sclera proper. The innerlayer of the sclera consisted of dense connective tissues with twocartilaginous parts continuing over the oraserrata that composeddense connective fibers and ossicles.