Optical properties, mitochondria, and sutures of lenses of fishes: a comparative study of nine species

This comparative study of lenses from nine fish species consisted of seven teleosts (oscar, Astronotus ocellatus; smallmouth bass, Micropterus dolomieu; orangespotted sunfish, Lepomis humilus; Arctic char, Salvelinus alpinus; common carp, Cyprinus carpio; rainbow trout, Oncorhynchus mykiss; American eel, Anguilla rostrata) and two species representing more primitive forms (brook lamprey, Lampetra lamotteni; lake sturgeon, Acipenser fulvescens). Lens optical properties were analysed using an automated scanning laser monitor. Lens suture anatomy and the morphology and distribution of mitochondria were analysed using a confocal laser scanning microscope. Lenses of Arctic char exhibited the sharpest focus, whereas American eel lenses exhibited the poorest ability to focus and the highest amount of spherical aberration. Metabolically active mitochondria are found in lens epithelia] and superficial cortical fibre cells, as in mammals. The results of the detailed study of the lens sutures show that teleost lenses exhibit "line" sutures, whereas "Y" sutures are seen in lake sturgeon lenses. Line sutures are also seen in lenses of brook lamprey and American eel. These last results contrast with the common report of "point" sutures in fish lenses.