Purchase this article with an account.
S.A. Miles, P.A. Lewis, L. Archbald, D.A. Samuelson; Ciliary Body Angioarchitecture of Four Cetacean Species: Tursiops truncatus, Globicephela macroryhncus, Kogia breviceps and K. simus . Invest. Ophthalmol. Vis. Sci. 2003;44(13):654.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose:Ocular vascular patterns in large marine mammals, i.e. cetaceans, have not been studied. In order to begin to understand how the vascularization in the visual system of these animals may have evolved to serve large eyes and handle hydrostatic pressure changes, and perhaps even serve in the accommodative process, we have examined the vascular patterns within the ciliary body of four species of whales indigenous to Florida's waters. Apparent evolutionary differences which may aid in visual capabilities have been described. Methods: The anterior uvea of Tursiops truncatus, Globicephala macrorhyncus, Kogia breviceps and K. simus were examined in this study. Each specimen was collected post-mortem, from animals that had beached along the Floridian coastline, and placed in 10% formalin. The methods used to examine ocular tissue included gross inspection by stereomicroscopy and manual measurements, histological examination by light microscopy, and analysis of vascular patterns by three-dimensional reconstruction of digitally rendered serial sections. Masson's trichrome and Hematoxylin & Eosin were used to aid in visualization of blood vessels and other structures of interest. Results: Vascular patterns varied somewhat in their method of arteriolar supply. In the coastal dwelling T. truncatus, blood was supplied to the ciliary body by one arteriole branching from the major arteriole circle (MAC). In G. macrorhyncus, K. breviceps and K. simus, species that spend more time in deeper waters, capillary beds were supplied by multiple arterioles stemming from the MAC. In every instance, the arterioles gave rise to capillary beds housed within iridal processes that flowed posteriorly into the ciliary processes. Venous outflow was largely similar in all species, with the venous system being more elaborately designed in K. breviceps. Veins draining the ciliary process emptied into the anterior-most choroidal veins. Encapsulated corpuscles were present in each specimen, having varied in location within the filtration angle and adjacent regions. Conclusions: A highly developed vascular system within the ciliary body, along with the presence of encapsulated corpuscles within the filtration angle and/or the corneo-scleral junction, are features that comprise a design not seen in any specific terrestrial mammal. These features, along with unusual iridal and corneal features, may enhance vision and compensate for a loss of ciliary body musculature.
This PDF is available to Subscribers Only